Prkaa2

UniProt ID: Q09137
Organism: Rattus norvegicus
Review Status: IN PROGRESS
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Gene Description

PRKAA2 encodes the alpha-2 catalytic subunit of AMP-activated protein kinase (AMPK), a central cellular energy sensor that maintains energy homeostasis. As a serine/threonine kinase, PRKAA2 is activated when cellular AMP/ATP ratios rise, triggering phosphorylation of metabolic enzymes to suppress anabolic processes (fatty acid/cholesterol synthesis) while promoting catabolic processes (fatty acid oxidation, glycolysis, autophagy). The protein forms heterotrimeric complexes with regulatory beta and gamma subunits, localizes to both cytoplasm and nucleus, and phosphorylates key substrates including ACC (fatty acid synthesis), HMGCR (cholesterol synthesis), PFK-2 (glycolysis), and ChREBP (transcriptional regulation). Recent discoveries highlight its direct role in chromatin remodeling via histone H2B phosphorylation under stress conditions.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0004674 protein serine/threonine kinase activity
IBA
GO_REF:0000033 		ACCEPT
Summary: Core catalytic function strongly supported by extensive biochemical evidence. PRKAA2 phosphorylates serine/threonine residues on numerous substrates (ACC, HMGCR, PFK-2, ChREBP, TSC2, Raptor). Multiple IDA studies confirm this activity (PMID:8955377, PMID:12065578).
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research.md
Generated using OpenAI Deep Research API
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
Prkaa2 encodes a **protein kinase** (EC 2.7.11.1; Ser/Thr kinase).
GO:0010508 positive regulation of autophagy
IBA
GO_REF:0000033 		KEEP AS NON CORE
Summary: Well-established function through ULK1 phosphorylation and mTORC1 inhibition. However, 2024 research shows complexity - AMPK can suppress autophagy in specific contexts. Keep as important but context-dependent function.
GO:0042149 cellular response to glucose starvation
IBA
GO_REF:0000033 		ACCEPT
Summary: Core function - AMPK is the primary cellular glucose/energy sensor. Activated by low glucose via AMP/ATP ratio changes. Knockout mice show impaired glucose homeostasis. Multiple ISS/ISO annotations support this.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation.
GO:0006338 chromatin remodeling
IEA
GO_REF:0000108 		ACCEPT
Summary: Supported by evidence that AMPK/PRKAA2 phosphorylates histone H2B under metabolic stress, linking energy sensing to chromatin remodeling.
Reason: Chromatin remodeling is supported by histone H2B Ser36 phosphorylation in stress conditions, aligning with core_functions that capture this epigenetic regulation.
GO:0004672 protein kinase activity
IEA
GO_REF:0000002 		REMOVE
Summary: Too general - more specific terms available (serine/threonine kinase, AMP-activated protein kinase). Redundant with better-annotated specific terms.
GO:0004679 AMP-activated protein kinase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Core defining function of PRKAA2. Multiple IDA studies confirm (PMID:11069105, PMID:11724780, PMID:14511394). This is THE primary molecular function.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation.
GO:0005524 ATP binding
IEA
GO_REF:0000120 		ACCEPT
Summary: Essential for kinase function - ATP is the phosphate donor. IDA evidence exists (PMID:16648175). Crystal structures confirm ATP-binding pocket.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
The α subunit provides the **catalytic kinase activity** and is activated primarily by phosphorylation at a conserved threonine within the activation loop (**Thr172 for α2**), which is a core mechanistic definition of “AMPK activation.”
GO:0000166 nucleotide binding
IEA
GO_REF:0000043 		REMOVE
Summary: Too general - ATP binding is more specific and already annotated. Redundant.
GO:0004674 protein serine/threonine kinase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Automated annotation consistent with IBA and IDA evidence. Core kinase function.
GO:0006325 chromatin organization
IEA
GO_REF:0000043 		MARK AS OVER ANNOTATED
Summary: Weak IEA evidence. While H2B phosphorylation occurs, this is stress-specific and not a primary function. Too broad.
GO:0006629 lipid metabolic process
IEA
GO_REF:0000043 		ACCEPT
Summary: Core function via ACC and HMGCR phosphorylation. Controls fatty acid and cholesterol synthesis. Strong experimental support (PMID:12065578). However, more specific terms available.
GO:0006631 fatty acid metabolic process
IEA
GO_REF:0000043 		ACCEPT
Summary: Core function - directly regulates ACC to control fatty acid synthesis/oxidation balance. IDA evidence for fatty acid homeostasis (PMID:11724780).
GO:0006633 fatty acid biosynthetic process
IEA
GO_REF:0000043 		REMOVE
Summary: AMPK actually INHIBITS fatty acid synthesis by phosphorylating ACC. This annotation implies positive regulation which is incorrect.
GO:0006694 steroid biosynthetic process
IEA
GO_REF:0000043 		REMOVE
Summary: Too broad and AMPK generally inhibits steroid/cholesterol synthesis. More specific negative regulation terms would be appropriate.
GO:0006695 cholesterol biosynthetic process
IEA
GO_REF:0000043 		REMOVE
Summary: AMPK INHIBITS cholesterol synthesis via HMGCR phosphorylation. This term implies positive regulation which is incorrect.
GO:0006914 autophagy
IEA
GO_REF:0000043 		REMOVE
Summary: Too broad - 'positive regulation of autophagy' is more accurate. Complex bidirectional regulation discovered in 2024.
GO:0008202 steroid metabolic process
IEA
GO_REF:0000043 		REMOVE
Summary: Too broad. AMPK's role is more specific to cholesterol metabolism inhibition.
GO:0008203 cholesterol metabolic process
IEA
GO_REF:0000043 		ACCEPT
Summary: AMPK regulates cholesterol metabolism primarily through HMGCR inhibition. Keep but note the regulatory direction.
Reason: PRKAA2 directly phosphorylates and inhibits HMGCR, making cholesterol metabolism a core regulated process in energy stress.
GO:0016055 Wnt signaling pathway
IEA
GO_REF:0000043 		MARK AS OVER ANNOTATED
Summary: Weak evidence, likely indirect effect. May phosphorylate beta-catenin but not a primary function. IEA only.
GO:0016126 sterol biosynthetic process
IEA
GO_REF:0000043 		REMOVE
Summary: AMPK inhibits rather than promotes sterol synthesis. Misleading annotation.
GO:0016301 kinase activity
IEA
GO_REF:0000043 		REMOVE
Summary: Too general - more specific terms (protein serine/threonine kinase, AMP-activated protein kinase) are already annotated.
GO:0016740 transferase activity
IEA
GO_REF:0000043 		REMOVE
Summary: Far too general - specific kinase terms already present. No value added.
GO:0031000 response to caffeine
IEA
GO_REF:0000117 		KEEP AS NON CORE
Summary: IDA evidence exists (PMID:19608206) showing caffeine activates AMPK in muscle. However, this is a pharmacological response, not a core function.
GO:0045821 positive regulation of glycolytic process
IEA
GO_REF:0000117 		ACCEPT
Summary: Core function - AMPK phosphorylates PFK-2 at Ser466 to activate glycolysis. Strong IDA evidence (PMID:11069105). Critical for ATP generation under stress.
GO:0046872 metal ion binding
IEA
GO_REF:0000043 		MODIFY
Summary: Mg2+ binding is required for kinase activity (coordinates ATP). Standard feature of protein kinases. Could be more specific.
Proposed replacements: magnesium ion binding
GO:0047322 [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Specific substrate phosphorylation well-documented (PMID:2369897). Important for cholesterol homeostasis. Keep as it provides mechanistic specificity.
GO:0048511 rhythmic process
IEA
GO_REF:0000043 		REMOVE
Summary: Too vague. 'Regulation of circadian rhythm' is more specific and has better evidence. Redundant.
GO:0055089 fatty acid homeostasis
IEA
GO_REF:0000117 		ACCEPT
Summary: Core function with strong IDA evidence (PMID:11724780). AMPK balances fatty acid synthesis/oxidation via ACC phosphorylation.
GO:0071277 cellular response to calcium ion
IEA
GO_REF:0000117 		KEEP AS NON CORE
Summary: AMPK is activated by CaMKK2 in response to calcium. IMP evidence exists (PMID:25788287). Important regulatory mechanism but not primary function.
GO:0071333 cellular response to glucose stimulus
IEA
GO_REF:0000117 		ACCEPT
Summary: Core function - responds to both high and low glucose. IMP evidence (PMID:25788287). Central to glucose homeostasis.
GO:0097009 energy homeostasis
IEA
GO_REF:0000117 		ACCEPT
Summary: THE core function of AMPK - master regulator of cellular energy balance. Strong IDA evidence (PMID:11724780). Fundamental role.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
Functionally, AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy
GO:0106310 protein serine kinase activity
IEA
GO_REF:0000116 		REMOVE
Summary: Redundant with 'protein serine/threonine kinase activity' which is more complete and has better evidence.
GO:0031669 cellular response to nutrient levels
ISO
GO_REF:0000096 		ACCEPT
Summary: Core function - AMPK senses and responds to nutrient availability. Strong ISO evidence from mouse. Fundamental role in metabolism. RETIRED - GO_REF:0000096 no longer used in GOA.
GO:0004679 AMP-activated protein kinase activity
ISO
GO_REF:0000096 		ACCEPT
Summary: Duplicate annotation - core AMPK function already reviewed as IBA evidence type. This ISO annotation provides additional ortholog-based support for the same function. RETIRED - GO_REF:0000096 no longer used in GOA.
GO:0004674 protein serine/threonine kinase activity
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog-based annotation consistent with IBA and IDA evidence. Core kinase function. RETIRED - GO_REF:0000096 no longer used in GOA.
GO:0140823 histone H2BS36 kinase activity
ISS
GO_REF:0000024 		ACCEPT
Summary: Evidence for H2B Ser36 phosphorylation by AMPK under stress conditions is well-established in mammals. This is a specific stress-response function supported by experimental data.
GO:0140823 histone H2BS36 kinase activity
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog evidence for H2B Ser36 phosphorylation under stress conditions.
GO:0004679 AMP-activated protein kinase activity
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		ACCEPT
Summary: Strong evidence - PMID:25788287 shows calcium-dependent AMPK activation in neurons. IMP evidence for core AMPK function.
Supporting Evidence:
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal neurons
GO:0042149 cellular response to glucose starvation
ISS
GO_REF:0000024 		ACCEPT
Summary: Sequence similarity evidence for glucose starvation response. Core AMPK function.
GO:0042149 cellular response to glucose starvation
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog evidence for glucose starvation response. Core AMPK function.
GO:1905691 lipid droplet disassembly
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: AMPK promotes lipolysis and lipid droplet breakdown via phosphorylation of lipases and metabolic enzymes. This is supported by evidence of AMPK activating lipid oxidation pathways.
GO:1905691 lipid droplet disassembly
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for AMPK role in lipid droplet breakdown.
GO:0062028 regulation of stress granule assembly
ISO
GO_REF:0000096 		MARK AS OVER ANNOTATED
Summary: AMPK responds to stress conditions and may influence stress granule formation, but evidence is indirect. Likely over-annotation as not a primary function.
GO:0010629 negative regulation of gene expression
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: AMPK negatively regulates lipogenic genes (ChREBP, SREBP) and anabolic gene programs. However, term is too broad - more specific terms would be better.
GO:0034599 cellular response to oxidative stress
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: AMPK is activated during oxidative stress and promotes protective responses including autophagy. This is a legitimate stress response function.
GO:0070507 regulation of microtubule cytoskeleton organization
ISO
GO_REF:0000096 		MARK AS OVER ANNOTATED
Summary: Weak evidence - AMPK may indirectly affect cytoskeleton but this is not a well-established primary function. Likely over-annotation.
GO:0071277 cellular response to calcium ion
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for calcium-dependent AMPK activation. Important regulatory mechanism.
GO:0071277 cellular response to calcium ion
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		KEEP AS NON CORE
Summary: Strong evidence - PMID:25788287 demonstrates calcium-dependent AMPK activation via CaMKK2 pathway. Important regulatory mechanism but not core metabolic function.
Supporting Evidence:
PMID:25788287
2015 Mar 18. Polarized activities of AMPK and BRSK in primary hippocampal neurons.
GO:0071333 cellular response to glucose stimulus
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog evidence for glucose response. Core AMPK function.
GO:0071333 cellular response to glucose stimulus
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		ACCEPT
Summary: Strong supporting evidence for core glucose sensing function. IMP evidence adds to already accepted IEA annotation.
Supporting Evidence:
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal neurons
GO:0010468 regulation of gene expression
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Too broad - AMPK regulates specific gene sets via ChREBP, SREBP, p53, etc. More specific terms would be preferable.
GO:0014850 response to muscle activity
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Well-established function - AMPK is activated during muscle contraction and exercise. Important for muscle energy metabolism adaptation.
GO:0071466 cellular response to xenobiotic stimulus
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: AMPK can be activated by xenobiotics like AICAR, metformin, and other compounds. Secondary response, not core function.
GO:0016241 regulation of macroautophagy
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: More specific than general autophagy term. AMPK regulates macroautophagy via ULK1 phosphorylation and mTORC1 inhibition. Established function.
GO:0016241 regulation of macroautophagy
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for macroautophagy regulation. Established function.
GO:0071380 cellular response to prostaglandin E stimulus
ISO
GO_REF:0000096 		MARK AS OVER ANNOTATED
Summary: Very specific response that may occur but is not well-documented as primary function. Likely over-annotation.
GO:0004712 protein serine/threonine/tyrosine kinase activity
ISO
GO_REF:0000096 		REMOVE
Summary: AMPK is primarily serine/threonine kinase, not tyrosine. This broader term is less accurate than the specific serine/threonine kinase annotation.
GO:0003682 chromatin binding
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: AMPK translocates to nucleus under stress and binds chromatin to phosphorylate histones. Evidence from H2B phosphorylation studies supports this.
GO:0003682 chromatin binding
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for chromatin binding during stress responses.
GO:0004679 AMP-activated protein kinase activity
IDA
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a ... 		ACCEPT
Summary: Strong direct evidence for core AMPK function. PMID:11069105 demonstrates AMPK phosphorylation of PFK-2, confirming kinase activity.
Supporting Evidence:
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a role in the stimulation of glycolysis during ischaemia
GO:0004679 AMP-activated protein kinase activity
IDA
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced... 		ACCEPT
Summary: Strong direct evidence for core AMPK function. PMID:11724780 demonstrates AMPK phosphorylation of ChREBP, confirming kinase activity.
Supporting Evidence:
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced transcription: regulation of carbohydrate-responsive element-binding protein by AMP-activated protein kinase
GO:0005515 protein binding
IPI
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a ... 		REMOVE
Summary: Too general - AMPK binds many proteins but more specific terms would be better (complex binding, substrate binding). Remove as uninformative.
Supporting Evidence:
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a role in the stimulation of glycolysis during ischaemia.
GO:0005515 protein binding
IPI
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced... 		REMOVE
Summary: Too general - AMPK binds many proteins but more specific terms would be better. Remove as uninformative.
Supporting Evidence:
PMID:11724780
Nov 27. Mechanism for fatty acid "sparing" effect on glucose-induced transcription: regulation of carbohydrate-responsive element-binding protein by AMP-activated protein kinase.
GO:0008610 lipid biosynthetic process
ISS
GO_REF:0000024 		REMOVE
Summary: Misleading - AMPK actually INHIBITS lipid biosynthesis by phosphorylating ACC and other enzymes. This should be negative regulation.
GO:0008610 lipid biosynthetic process
ISO
GO_REF:0000096 		REMOVE
Summary: Misleading - AMPK actually INHIBITS lipid biosynthesis. Remove incorrect annotation.
GO:0010508 positive regulation of autophagy
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: Sequence similarity evidence for autophagy regulation. Complex context-dependent function.
GO:0010508 positive regulation of autophagy
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for autophagy regulation. Complex context-dependent function.
GO:0031669 cellular response to nutrient levels
ISS
GO_REF:0000024 		ACCEPT
Summary: Sequence similarity evidence for nutrient sensing. Core AMPK function.
GO:0032007 negative regulation of TOR signaling
ISS
GO_REF:0000024 		ACCEPT
Summary: Core function - AMPK inhibits mTORC1 via TSC2 and Raptor phosphorylation. Well-established mechanism for energy conservation.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
GO:0032007 negative regulation of TOR signaling
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog evidence for TOR inhibition. Core metabolic regulation.
GO:0042752 regulation of circadian rhythm
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: AMPK phosphorylates CRY1 and links metabolism to circadian rhythms. However, this is not a primary metabolic function.
GO:0042752 regulation of circadian rhythm
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for circadian regulation via CRY1 phosphorylation.
GO:0043066 negative regulation of apoptotic process
ISS
GO_REF:0000024 		KEEP AS NON CORE
Summary: AMPK can promote cell survival during mild stress via autophagy and p53 phosphorylation. Context-dependent protective function.
GO:0043066 negative regulation of apoptotic process
ISO
GO_REF:0000096 		KEEP AS NON CORE
Summary: Ortholog evidence for cell survival promotion during stress.
GO:0045821 positive regulation of glycolytic process
IDA
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a ... 		ACCEPT
Summary: Strong direct evidence - PMID:11069105 demonstrates AMPK phosphorylation of PFK-2 which activates glycolysis. Core metabolic function.
Supporting Evidence:
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a role in the stimulation of glycolysis during ischaemia
GO:0055089 fatty acid homeostasis
IDA
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced... 		ACCEPT
Summary: Strong direct evidence - PMID:11724780 shows AMPK regulation of fatty acid metabolism via ACC phosphorylation. Core function already accepted from IEA.
Supporting Evidence:
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced transcription: regulation of carbohydrate-responsive element-binding protein by AMP-activated protein kinase
GO:0097009 energy homeostasis
IDA
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced... 		ACCEPT
Summary: Strong direct evidence - PMID:11724780 demonstrates AMPK role in cellular energy balance. THE core function already accepted from IEA.
Supporting Evidence:
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced transcription: regulation of carbohydrate-responsive element-binding protein by AMP-activated protein kinase
GO:0042593 glucose homeostasis
ISS
GO_REF:0000024 		ACCEPT
Summary: Core function - AMPK is central to glucose homeostasis through multiple mechanisms. Well-established role in glucose metabolism.
GO:0042593 glucose homeostasis
ISO
GO_REF:0000096 		ACCEPT
Summary: Ortholog evidence for glucose homeostasis. Core metabolic function.
GO:0014823 response to activity
IDA
PMID:17253964
Adrenaline is a critical mediator of acute exercise-induced ... 		KEEP AS NON CORE
Summary: PMID:17253964 shows adrenergic activation of AMPK in adipocytes during activity. Important physiological response but not core function.
Supporting Evidence:
PMID:17253964
Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes.
GO:0031000 response to caffeine
IDA
PMID:19608206
Caffeine acutely activates 5'adenosine monophosphate-activat... 		KEEP AS NON CORE
Summary: Strong direct evidence - PMID:19608206 shows caffeine activates AMPK in skeletal muscle. Pharmacological response already accepted from IEA.
Supporting Evidence:
PMID:19608206
2009 Jul 15. Caffeine acutely activates 5'adenosine monophosphate-activated protein kinase and increases insulin-independent glucose transport in rat skeletal muscles.
GO:0004679 AMP-activated protein kinase activity
IDA
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/bet... 		ACCEPT
Summary: Strong direct evidence - PMID:14511394 demonstrates AMPK complexes and upstream kinase LKB1. Direct confirmation of kinase activity.
Supporting Evidence:
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase cascade
GO:0044877 protein-containing complex binding
IDA
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/bet... 		KEEP AS NON CORE
Summary: PMID:14511394 shows AMPK interaction with LKB1-STRD-MO25 complex. Specific complex binding is more informative than general protein binding.
Supporting Evidence:
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase cascade.
GO:0004674 protein serine/threonine kinase activity
IDA
PMID:8955377
The alpha1 and alpha2 isoforms of the AMP-activated protein ... 		ACCEPT
Summary: Strong direct evidence - PMID:8955377 demonstrates substrate specificity differences between α1 and α2 isoforms. Core kinase function.
Supporting Evidence:
PMID:8955377
The alpha1 and alpha2 isoforms of the AMP-activated protein kinase have similar activities in rat liver but exhibit differences in substrate specificity in vitro.
GO:0004679 AMP-activated protein kinase activity
IMP
PMID:10698692
Characterization of AMP-activated protein kinase gamma-subun... 		ACCEPT
Summary: IMP evidence from γ subunit characterization study. Shows requirement for γ subunit in AMP binding and AMPK activation.
Supporting Evidence:
PMID:10698692
Characterization of AMP-activated protein kinase gamma-subunit isoforms and their role in AMP binding
GO:0004679 AMP-activated protein kinase activity
IMP
PMID:8955377
The alpha1 and alpha2 isoforms of the AMP-activated protein ... 		ACCEPT
Summary: IMP evidence showing differential properties of α2 vs α1 complexes. Demonstrates AMP-activation specifically.
Supporting Evidence:
PMID:8955377
The alpha1 and alpha2 isoforms of the AMP-activated protein kinase have similar activities in rat liver but exhibit differences in substrate specificity in vitro.
GO:0030674 protein-macromolecule adaptor activity
IDA
PMID:15695819
AMP-activated protein kinase beta subunit tethers alpha and ... 		REMOVE
Summary: PMID:15695819 shows β subunit tethering α and γ subunits. However, this refers to β subunit function, not α2 directly.
Supporting Evidence:
PMID:15695819
2005 Jan 28. AMP-activated protein kinase beta subunit tethers alpha and gamma subunits via its C-terminal sequence (186-270).
GO:0004679 AMP-activated protein kinase activity
IDA
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the... 		ACCEPT
Summary: Strong direct evidence - PMID:16648175 shows AMPK activation in ischemic heart. Direct biochemical demonstration of kinase activity.
Supporting Evidence:
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the intact ischemic rat heart
GO:0005515 protein binding
IPI
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the... 		REMOVE
Summary: Too general - while AMPK binds proteins, more specific terms are preferable. Remove as uninformative.
Supporting Evidence:
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the intact ischemic rat heart.
GO:0005524 ATP binding
IDA
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the... 		ACCEPT
Summary: Strong evidence - PMID:16648175 demonstrates ATP requirement for AMPK activity. Core function already accepted from IEA.
Supporting Evidence:
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the intact ischemic rat heart
GO:0004672 protein kinase activity
IDA
PMID:12065578
Coordinate regulation of malonyl-CoA decarboxylase, sn-glyce... 		REMOVE
Summary: Too general - more specific serine/threonine and AMP-activated kinase terms already accepted. Remove redundant broad term.
Supporting Evidence:
PMID:12065578
2002 Jun 13. Coordinate regulation of malonyl-CoA decarboxylase, sn-glycerol-3-phosphate acyltransferase, and acetyl-CoA carboxylase by AMP-activated protein kinase in rat tissues in response to exercise.
GO:0019216 regulation of lipid metabolic process
IDA
PMID:12065578
Coordinate regulation of malonyl-CoA decarboxylase, sn-glyce... 		ACCEPT
Summary: Strong evidence - PMID:12065578 shows AMPK regulation of ACC and other lipid metabolic enzymes. Well-established function.
Supporting Evidence:
PMID:12065578
Coordinate regulation of malonyl-CoA decarboxylase, sn-glycerol-3-phosphate acyltransferase, and acetyl-CoA carboxylase by AMP-activated protein kinase in rat tissues in response to exercise
GO:0005634 nucleus
IBA
GO_REF:0000033 		ACCEPT
Summary: AMPK localizes to both cytoplasm and nucleus depending on cellular conditions. Nuclear localization is particularly important for its histone H2B phosphorylation function and direct transcriptional regulation under stress conditions. The α2 subunit can translocate to nucleus where it phosphorylates chromatin targets and interacts with transcriptional machinery.
Reason: Nuclear localization is essential for AMPK's stress-responsive chromatin modifying activities and direct transcriptional regulation, representing a key aspect of its energy-sensing function beyond cytoplasmic metabolism.
GO:0005737 cytoplasm
IBA
GO_REF:0000033 		ACCEPT
Summary: The cytoplasm is the primary location for AMPK's core metabolic regulatory functions. Here AMPK phosphorylates key metabolic enzymes including ACC (fatty acid synthesis), PFK-2 (glycolysis), HMGCR (cholesterol synthesis), and TSC2/Raptor (mTORC1 signaling). The majority of AMPK's energy-sensing and metabolic control activities occur in this compartment.
Reason: Cytoplasmic localization is fundamental to AMPK's primary role as a metabolic energy sensor. Most of its well-characterized substrate phosphorylation events occur in the cytoplasm where metabolic enzymes and signaling complexes are located.
GO:1904262 negative regulation of TORC1 signaling
IBA
GO_REF:0000033 		ACCEPT
Summary: AMPK directly inhibits mTORC1 by phosphorylating TSC2 and Raptor, a well-established energy-conservation mechanism. This TORC1-specific term is more precise than the generic negative regulation of TOR signaling annotation and reflects a core downstream signaling role.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
GO:1990044 protein localization to lipid droplet
IBA
GO_REF:0000033 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0031588 nucleotide-activated protein kinase complex
IBA
GO_REF:0000033 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005634 nucleus
IEA
GO_REF:0000120 		ACCEPT
Summary: Automated annotation consistent with experimental evidence. Nuclear localization supports stress-responsive functions including histone phosphorylation and transcriptional regulation.
Reason: Supports the manually curated IBA annotation with additional automated evidence for nuclear localization.
GO:0005737 cytoplasm
IEA
GO_REF:0000120 		ACCEPT
Summary: Automated annotation consistent with experimental evidence. Cytoplasmic localization is where AMPK performs most of its metabolic regulatory functions through substrate phosphorylation.
Reason: Supports the manually curated IBA annotation with additional automated evidence for cytoplasmic localization.
GO:0030424 axon
IEA
GO_REF:0000117 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0030425 dendrite
IEA
GO_REF:0000117 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0031588 nucleotide-activated protein kinase complex
IEA
GO_REF:0000117 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0043025 neuronal cell body
IEA
GO_REF:0000117 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005634 nucleus
ISO
GO_REF:0000121 		ACCEPT
Summary: Ortholog-based annotation from mouse-rat comparisons. Nuclear localization is conserved across mammalian AMPK α2 subunits for stress-responsive chromatin functions.
Reason: Strong orthology evidence supports nuclear localization, consistent with other annotation types.
GO:0031588 nucleotide-activated protein kinase complex
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0031669 cellular response to nutrient levels
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0004679 AMP-activated protein kinase activity
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0005829 cytosol
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005654 nucleoplasm
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005794 Golgi apparatus
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0016607 nuclear speck
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0036064 ciliary basal body
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:1904262 negative regulation of TORC1 signaling
ISS
GO_REF:0000024 		ACCEPT
Summary: Sequence-similarity support for AMPK-mediated inhibition of mTORC1 via TSC2/Raptor phosphorylation. Consistent with the curated IBA annotation for this TORC1-specific term.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
GO:1904262 negative regulation of TORC1 signaling
ISO
GO_REF:0000121 		ACCEPT
Summary: Ortholog-based support for AMPK-mediated inhibition of mTORC1. Consistent with the curated IBA/ISS annotations for this TORC1-specific term.
GO:0002181 cytoplasmic translation
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0009267 cellular response to starvation
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0034198 cellular response to amino acid starvation
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0038202 TORC1 signaling
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0042149 cellular response to glucose starvation
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0045947 negative regulation of translational initiation
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0045948 positive regulation of translational initiation
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0061462 protein localization to lysosome
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0085020 protein K6-linked ubiquitination
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:1904263 positive regulation of TORC1 signaling
ISO
GO_REF:0000121 		REMOVE
Summary: Direction contradicts AMPK's canonical and well-established role - AMPKα2 is a negative regulator of mTORC1 (via TSC2/Raptor phosphorylation), not a positive regulator. This ortholog-transferred annotation attributes the opposite regulatory direction and is factually incorrect, not merely imprecise, so it should be removed.
Supporting Evidence:
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
GO:0004674 protein serine/threonine kinase activity
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0140823 histone H2BS36 kinase activity
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:1905691 lipid droplet disassembly
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:1990044 protein localization to lipid droplet
ISS
GO_REF:0000024 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:1990044 protein localization to lipid droplet
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0006646 phosphatidylethanolamine biosynthetic process
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0006656 phosphatidylcholine biosynthetic process
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0090200 positive regulation of release of cytochrome c from mitochondria
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0097284 hepatocyte apoptotic process
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:1903944 negative regulation of hepatocyte apoptotic process
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005737 cytoplasm
ISO
GO_REF:0000121 		ACCEPT
Summary: Ortholog-based annotation from mouse-rat comparisons. Cytoplasmic localization is conserved across mammalian AMPK α2 subunits for metabolic regulatory functions.
Reason: Strong orthology evidence supports cytoplasmic localization, consistent with other annotation types and functional requirements.
GO:0062028 regulation of stress granule assembly
ISO
GO_REF:0000121 		MARK AS OVER ANNOTATED
Summary: Likely over-annotation; term is too broad for PRKAA2.
GO:0010494 cytoplasmic stress granule
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0010629 negative regulation of gene expression
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0030424 axon
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0030424 axon
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:25788287
2015 Mar 18. Polarized activities of AMPK and BRSK in primary hippocampal neurons.
GO:0030425 dendrite
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0030425 dendrite
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:25788287
2015 Mar 18. Polarized activities of AMPK and BRSK in primary hippocampal neurons.
GO:0034599 cellular response to oxidative stress
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0043025 neuronal cell body
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0043025 neuronal cell body
IMP
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:25788287
2015 Mar 18. Polarized activities of AMPK and BRSK in primary hippocampal neurons.
GO:0070507 regulation of microtubule cytoskeleton organization
ISO
GO_REF:0000121 		MARK AS OVER ANNOTATED
Summary: Likely over-annotation; term is too broad for PRKAA2.
GO:0071277 cellular response to calcium ion
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0071333 cellular response to glucose stimulus
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:1903829 positive regulation of protein localization
ISO
GO_REF:0000121 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0010468 regulation of gene expression
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0014850 response to muscle activity
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0071466 cellular response to xenobiotic stimulus
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0016241 regulation of macroautophagy
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0071380 cellular response to prostaglandin E stimulus
ISO
GO_REF:0000121 		MARK AS OVER ANNOTATED
Summary: Likely over-annotation; term is too broad for PRKAA2.
GO:0004712 protein serine/threonine/tyrosine kinase activity
ISO
GO_REF:0000121 		REMOVE
Summary: Annotation is overly general or unsupported in this context and should be removed.
GO:0003682 chromatin binding
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0008610 lipid biosynthetic process
ISO
GO_REF:0000121 		REMOVE
Summary: Annotation is overly general or unsupported in this context and should be removed.
GO:0010508 positive regulation of autophagy
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0032007 negative regulation of TOR signaling
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0042752 regulation of circadian rhythm
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0043066 negative regulation of apoptotic process
ISO
GO_REF:0000121 		KEEP AS NON CORE
Summary: Evidence supports the term but it is not core to PRKAA2 function.
GO:0042593 glucose homeostasis
ISO
GO_REF:0000121 		ACCEPT
Summary: ISO annotation consistent with curated evidence for this term.
GO:0005737 cytoplasm
IDA
PMID:18256313
Control of glycogen synthase through ADIPOR1-AMPK pathway in... 		ACCEPT
Summary: Direct experimental evidence from PMID:18256313 showing AMPK localization in renal epithelial cells. Cytoplasmic localization is essential for AMPK's role in controlling glycogen synthase and other metabolic targets in response to energy stress.
Reason: Strong experimental evidence for cytoplasmic localization where AMPK performs its primary metabolic regulatory functions.
Supporting Evidence:
PMID:18256313
Control of glycogen synthase through ADIPOR1-AMPK pathway in renal distal tubules of normal and diabetic rats.
GO:0016324 apical plasma membrane
IDA
PMID:18256313
Control of glycogen synthase through ADIPOR1-AMPK pathway in... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:18256313
Control of glycogen synthase through ADIPOR1-AMPK pathway in renal distal tubules of normal and diabetic rats.
GO:0032991 protein-containing complex
IDA
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/bet... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase cascade.
GO:0031588 nucleotide-activated protein kinase complex
IDA
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the... 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
Supporting Evidence:
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the intact ischemic rat heart.
GO:0005654 nucleoplasm
TAS
Reactome:R-RNO-164087 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.
GO:0005654 nucleoplasm
TAS
Reactome:R-RNO-164106 		UNDECIDED
Summary: Not reviewed in this pass; requires literature review.

Core Functions

PRKAA2 executes ATP-dependent phosphorylation of key metabolic regulatory proteins in response to cellular AMP/ATP ratio changes. Primary phosphorylation targets include ACC (inhibiting fatty acid synthesis), PFK-2 (activating glycolysis), ChREBP (blocking lipogenic transcription), HMGCR (inhibiting cholesterol synthesis), and TSC2/Raptor (suppressing mTORC1). The kinase functions as part of a heterotrimeric complex activated by Thr172 phosphorylation when AMP levels rise, creating a molecular switch for cellular energy status.

Molecular Function:
AMP-activated protein kinase activity
Directly Involved In:
energy homeostasis fatty acid homeostasis positive regulation of glycolytic process cellular response to glucose starvation negative regulation of TOR signaling
Cellular Locations:
cytoplasm nucleus
Supporting Evidence:

Specifically phosphorylates HMG-CoA reductase at Ser872, inactivating the rate-limiting enzyme of cholesterol biosynthesis to conserve cellular energy and NADPH during metabolic stress.

Molecular Function:
[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
Directly Involved In:
cholesterol metabolic process
Supporting Evidence:

Under severe metabolic stress, phosphorylates histone H2B at Ser36 to directly modify chromatin and activate stress-response gene transcription, representing a direct epigenetic mechanism linking energy status to gene expression.

Molecular Function:
histone H2BS36 kinase activity
Directly Involved In:
chromatin remodeling
Cellular Locations:
nucleus
Supporting Evidence:
  • GO_REF:0000024

References

GO_REF:0000002
Gene Ontology annotation through association of InterPro records with GO terms.
GO_REF:0000024
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity.
GO_REF:0000033
Annotation inferences using phylogenetic trees
GO_REF:0000043
Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
GO_REF:0000096
Automated transfer of experimentally-verified manual GO annotation data to mouse-rat orthologs.
GO_REF:0000108
Automatic assignment of GO terms using logical inference, based on on inter-ontology links.
GO_REF:0000116
Automatic Gene Ontology annotation based on Rhea mapping.
GO_REF:0000117
Electronic Gene Ontology annotations created by ARBA machine learning models
GO_REF:0000120
Combined Automated Annotation using Multiple IEA Methods.
PMID:10698692
Characterization of AMP-activated protein kinase gamma-subunit isoforms and their role in AMP binding.
PMID:11069105
Phosphorylation and activation of heart PFK-2 by AMPK has a role in the stimulation of glycolysis during ischaemia.
PMID:11724780
Mechanism for fatty acid "sparing" effect on glucose-induced transcription: regulation of carbohydrate-responsive element-binding protein by AMP-activated protein kinase.
PMID:12065578
Coordinate regulation of malonyl-CoA decarboxylase, sn-glycerol-3-phosphate acyltransferase, and acetyl-CoA carboxylase by AMP-activated protein kinase in rat tissues in response to exercise.
PMID:14511394
Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase cascade.
PMID:15695819
AMP-activated protein kinase beta subunit tethers alpha and gamma subunits via its C-terminal sequence (186-270).
PMID:16648175
Activation of AMPK alpha- and gamma-isoform complexes in the intact ischemic rat heart.
PMID:17253964
Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes.
PMID:19608206
Caffeine acutely activates 5'adenosine monophosphate-activated protein kinase and increases insulin-independent glucose transport in rat skeletal muscles.
PMID:25788287
Polarized activities of AMPK and BRSK in primary hippocampal neurons.
PMID:8955377
The alpha1 and alpha2 isoforms of the AMP-activated protein kinase have similar activities in rat liver but exhibit differences in substrate specificity in vitro.
PMID:2369897
Regulation of HMG-CoA reductase: identification of the site phosphorylated by the AMP-activated protein kinase in vitro and in intact rat liver.
file:rat/Prkaa2/Prkaa2-deep-research.md
Deep research synthesis for PRKAA2 functions and regulation
file:rat/Prkaa2/Prkaa2-notes.md
Research notes on PRKAA2 with literature citations
file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
Falcon (Edison Scientific) deep research report for rat Prkaa2 (AMPKα2)
  • Prkaa2 encodes the catalytic alpha-2 subunit of the heterotrimeric AMPK serine/threonine kinase; the alpha subunit carries the catalytic kinase activity.
    "AMPK is a **heterotrimeric serine/threonine kinase** consisting of a **catalytic α** subunit plus **regulatory β and γ** subunits."
  • The alpha subunit provides the catalytic kinase activity and is activated by phosphorylation at Thr172 in the activation loop.
    "The α subunit provides the **catalytic kinase activity** and is activated primarily by phosphorylation at a conserved threonine within the activation loop (**Thr172 for α2**), which is a core mechanistic definition of “AMPK activation.”"
  • Prkaa2 is a protein serine/threonine kinase (EC 2.7.11.1).
    "Prkaa2 encodes a **protein kinase** (EC 2.7.11.1; Ser/Thr kinase)."
  • AMP binding (via the gamma subunit) allosterically activates AMPK and protects it from dephosphorylation, coupling ATP depletion to kinase activation — the basis of AMP-activated protein kinase activity.
    "AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation."
  • Upstream kinases phosphorylate AMPKα2 at Thr172, with LKB1 as a primary kinase and CaMKKβ/CAMKK2 as a calcium-responsive route.
    "upstream kinases phosphorylate AMPKα2 at **Thr172**, with **LKB1** frequently highlighted as a primary kinase"
  • AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy — its core energy-homeostasis role.
    "Functionally, AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy"
  • AMPK phosphorylates metabolic targets including ACC, HMGCR, and autophagy regulators such as ULK1.
    "AMPKα2 phosphorylates metabolic targets including ACC/ACAC (canonical readout; ACC Ser79 commonly used), HMGCR, and autophagy regulators such as ULK1"
  • AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor.
    "AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor"
  • AMPKα2 has a nuclear localization signal and can shuttle to the nucleus, whereas α1 is primarily cytosolic.
    "AMPKα2 contains a nuclear localization signal and can shuttle to the nucleus"
  • A 2024 primary study identifies an AMPKα2-specific role in skeletal muscle ketone utilization via binding and stabilization of SCOT.
    "These results place AMPKα2 as an important regulator of **skeletal muscle ketone utilization**"
GO_REF:0000121
RGD ISO annotations to rat from other mammalian species.
PMID:18256313
Control of glycogen synthase through ADIPOR1-AMPK pathway in renal distal tubules of normal and diabetic rats.
Reactome:R-RNO-164087
Phosphorylation of rChREBP(Ser 568) by rAMPK
Reactome:R-RNO-164106
rLkb-1 (Stk-11) activates AMPK by phosphorylation

Suggested Questions for Experts

Q: How do the α1 and α2 subunits of AMPK differ in their tissue distribution, regulation, and substrate specificity?

Q: What determines the subcellular localization of PRKAA2-containing AMPK complexes and how does this affect their function?

Q: How does PRKAA2 contribute to metabolic sensing and energy homeostasis in different physiological conditions?

Q: What role does PRKAA2 play in cellular stress responses beyond its canonical metabolic functions?

Q: Does AMPKα2's binding and stabilization of SCOT (succinyl-CoA:3-ketoacid CoA transferase) in skeletal muscle ketone utilization represent a broader non-catalytic scaffolding function, and can this stabilization mechanism be confirmed in rat tissues?

Suggested Experiments

Experiment: Proteomics analysis to identify PRKAA2-specific substrates and interacting partners compared to PRKAA1

Experiment: Live-cell imaging using FRET-based biosensors to monitor PRKAA2-containing AMPK activity in real-time

Experiment: Metabolomics analysis of tissues from PRKAA2 knockout mice to understand metabolic pathway alterations

Experiment: Single-cell analysis of AMPK activity and metabolic state in different cell types using genetically encoded indicators

Experiment: Co-immunoprecipitation and cycloheximide-chase protein stability assays in rat skeletal muscle to test whether AMPKα2 binds and stabilizes SCOT (succinyl-CoA:3-ketoacid CoA transferase) and limits its ubiquitin/proteasome-mediated degradation, probing a non-catalytic scaffolding role in ketone utilization

Deep Research

Falcon

(Prkaa2-deep-research-falcon.md)
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 25 citations 2 artifacts 2026-06-01T01:41:02.509714
Edison artifact artifact-00 (text/markdown)
## Context ID: pqac-00000018 The document provides schematic summaries of the AMPK complex in Figures 1 and 2. - **AMPK Complex Structure**: Both Figure 1 and F (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research Report: Rat Prkaa2 (AMPK catalytic subunit α2) — Functional Annotation

0) Target verification (critical disambiguation)

The target gene/protein is Prkaa2 from Rattus norvegicus (rat), corresponding to the catalytic α2 isoform of AMP-activated protein kinase (AMPKα2), orthologous to human PRKAA2. Multiple sources explicitly map Prkaa2/PRKAA2 → AMPKα2 and describe AMPK as a heterotrimeric Ser/Thr kinase with α as the catalytic subunit. (kim2025thelinkbetween pages 5-7, rakoubian2025isoformspecificrolesof pages 8-9, hauger2024shearstressinducedampactivated pages 2-4)

Note: Within the retrieved corpus, no full-text explicitly states the UniProt accession Q09137. However, the gene symbol, isoform, enzymatic class (Ser/Thr kinase), and activation-site/regulatory architecture in the literature match the UniProt-provided identity for rat AMPKα2. (kim2025thelinkbetween pages 5-7, ashraf2024finetuningampkin pages 2-2)

1) Key concepts and definitions (current understanding)

1.1 AMPK complex and what Prkaa2 encodes

AMPK is a heterotrimeric serine/threonine kinase consisting of a catalytic α subunit plus regulatory β and γ subunits. AMPKα exists as two isoforms (α1 and α2), encoded by Prkaa1/Prkaa2 in rodents (PRKAA1/PRKAA2 in humans). (kim2025thelinkbetween pages 5-7, hauger2024shearstressinducedampactivated pages 2-4)

The α subunit provides the catalytic kinase activity and is activated primarily by phosphorylation at a conserved threonine within the activation loop (Thr172 for α2), which is a core mechanistic definition of “AMPK activation.” (rakoubian2025isoformspecificrolesof pages 1-2, rakoubian2025isoformspecificrolesof pages 2-3)

1.2 Activation mechanisms: phosphorylation + allostery + compartmentalization

Canonical activation: upstream kinases phosphorylate AMPKα2 at Thr172, with LKB1 frequently highlighted as a primary kinase (particularly in cardiac contexts), and CaMKKβ/CAMKK2 as an alternate calcium-responsive route. (rakoubian2025isoformspecificrolesof pages 1-2, rakoubian2025isoformspecificrolesof pages 2-3)

Allosteric nucleotide sensing: AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation. (mohanty2025rethinkingampka pages 1-2)

Spatial regulation: recent work emphasizes compartmentalized AMPK pools (e.g., lysosomal AMPK) and demonstrates glucose starvation signaling in which AXIN–LKB1 translocates to lysosomes, promoting AMPK-dependent control of mTORC1 signaling. (li2023hierarchicalinhibitionof pages 3-4)

A schematic depiction of AMPK structure and activation (including Thr172 phosphorylation by LKB1/CAMKK2) is shown in figure crops retrieved from a 2024 review. (ashraf2024finetuningampkin media b6222dde, ashraf2024finetuningampkin media d3d7e38d)

1.3 Isoform-specific localization (α2 vs α1)

Isoform differences matter for functional annotation. A 2024 review summarizes that AMPKα2 contains a nuclear localization signal and can shuttle to the nucleus, whereas AMPKα1 has an export sequence and is primarily cytosolic. (ashraf2024finetuningampkin pages 2-2)

Consistent with this, a cardiac-focused review describes AMPKα2 as present in cytosol and nucleus in cardiomyocytes and emphasizes isoform-specific roles. (rakoubian2025isoformspecificrolesof pages 8-9)

2) Molecular function: reaction catalyzed and substrate specificity

2.1 Enzymatic activity

Prkaa2 encodes a protein kinase (EC 2.7.11.1; Ser/Thr kinase). The biochemical reaction is:

ATP + protein(Ser/Thr) → ADP + protein(Ser/Thr)-phosphate

This is operationalized in the literature by phosphorylation of well-established downstream substrates used as readouts of AMPK activation.

2.2 Canonical substrates and downstream processes

Across the evidence set, commonly referenced AMPK substrates include:
- Acetyl-CoA carboxylase (ACC/ACAC) phosphorylation (widely used as a downstream readout of AMPK activity) (li2023hierarchicalinhibitionof pages 3-4)
- HMG-CoA reductase (HMGCR) as a classical metabolic substrate (mohanty2025rethinkingampka pages 1-2)
- Autophagy pathway targets including ULK1 and upstream inhibition of mTORC1 (rakoubian2025isoformspecificrolesof pages 2-3, jang2023thrap3promotesnonalcoholic pages 1-2)

While not all residue numbers are available in the extracted snippets, the substrate set is consistent with AMPK’s established role: inhibiting anabolic lipid/cholesterol synthesis and promoting catabolic adaptation and autophagy/mitophagy under energy stress. (rakoubian2025isoformspecificrolesof pages 2-3, mohanty2025rethinkingampka pages 1-2)

3) Pathways and biological processes (with Prkaa2-specific evidence where possible)

3.1 Energy stress → lysosome → mTORC1 inhibition (2023 primary)

A 2023 study dissected glucose starvation signaling and concluded that AXIN lysosomal translocation plays a primary role in glucose starvation-triggered inhibition of mTORC1 (via inhibition of RAGs), while AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor, especially under severe stress conditions. Importantly, the paper distinguishes AXIN translocation from AMPK activity (AXIN translocation did not require AMPK), but AMPK activity contributed to mTORC1 inhibition kinetics and residual suppression. (li2023hierarchicalinhibitionof pages 3-4)

This provides a mechanistic pathway-level framework relevant to AMPKα2 function in nutrient sensing (though not strictly α2-exclusive in this experiment set). (li2023hierarchicalinhibitionof pages 3-4)

3.2 NAFLD/autophagy regulation with nuclear–cytosolic AMPK redistribution (2023 primary)

In a 2023 NAFLD model study, hepatic Thrap3 was increased in NAFLD conditions, and liver-specific Thrap3 knockout improved lipid accumulation and metabolic properties. Mechanistically, Thrap3 deficiency enhanced autophagy and mitochondrial function and increased cytosolic translocation of AMPK from the nucleus, enhancing AMPK activation via physical interaction (with translocation regulated by Thrap3’s C-terminal domain). (jang2023thrap3promotesnonalcoholic pages 1-2)

This supports a functional annotation in which AMPK localization and activation state are dynamically regulated in metabolic disease contexts, and AMPK-mediated autophagy is protective in NAFLD-like phenotypes. (jang2023thrap3promotesnonalcoholic pages 1-2)

3.3 AMPKα2-specific role in fasting ketone utilization via SCOT stabilization (2024 primary; quantitative)

A 2024 primary study provides unusually direct α2-isoform-specific physiology. In prolonged fasting (48 h), skeletal muscle-specific AMPKα2 loss produced larger effects on ketone handling than α1 loss:
- AMPKα2ΔMusc mice showed ~2-fold higher blood β-hydroxybutyrate (BHB). (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 2-3)
- AMPKα2ΔMyo mice showed ~1.5–1.6-fold higher blood BHB after 48 h fasting. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 3-4)
- BHB tolerance assays indicated slower ketone consumption in AMPKα2 muscle knockouts compared with controls. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 2-3)

Mechanistically, AMPKα2 binds and stabilizes SCOT (succinyl-CoA:3-ketoacid CoA transferase; a rate-limiting ketolysis enzyme) by suppressing its ubiquitination and proteasomal degradation; inhibiting AMPKα2 increased SCOT ubiquitination, and a kinase-dead AMPKα2 reduced SCOT binding and increased SCOT ubiquitination. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 5-6)

These results place AMPKα2 as an important regulator of skeletal muscle ketone utilization, expanding beyond the classical “AMPK phosphorylates metabolic enzymes” framing into direct regulation of ketolysis enzyme stability. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 5-6)

4) Subcellular localization: where the gene product acts

Evidence across sources supports multi-compartment operation:
- Nucleus/cytosol shuttling: AMPKα2 has a nuclear localization signal and can shuttle to the nucleus (isoform-biased relative to α1). (ashraf2024finetuningampkin pages 2-2)
- Nuclear–cytosolic redistribution in disease: NAFLD-related Thrap3 regulation alters AMPK distribution, with increased cytosolic translocation associated with increased AMPK activation. (jang2023thrap3promotesnonalcoholic pages 1-2)
- Lysosome-associated nutrient sensing: glucose starvation signaling positions AMPK activity within a lysosome-centered signaling hub through AXIN–LKB1 lysosomal translocation and downstream mTORC1 control. (li2023hierarchicalinhibitionof pages 3-4)

Together, these support annotating AMPKα2 as functioning in both cytosolic metabolic regulation and nuclear programs (via shuttling), with important regulation at organelle-associated signaling sites (e.g., lysosome). (ashraf2024finetuningampkin pages 2-2, li2023hierarchicalinhibitionof pages 3-4)

5) Recent developments and latest research (prioritizing 2023–2024)

Key 2023–2024 advances captured in the retrieved set include:
1. Lysosomal pathway hierarchy in glucose starvation: separation of AXIN lysosomal translocation effects from AMPK-dependent mTORC1 inhibition (a more refined view of nutrient stress signaling). (Published Mar 2023) (li2023hierarchicalinhibitionof pages 3-4)
2. NAFLD mechanism via AMPK compartmental regulation: Thrap3 acting as a negative regulator of AMPK-mediated autophagy in fatty liver disease models, implicating AMPK localization as a regulated step. (Published Aug 2023) (jang2023thrap3promotesnonalcoholic pages 1-2)
3. New α2-specific metabolic phenotype: AMPKα2 regulating systemic fasting ketone homeostasis through skeletal muscle ketolysis (SCOT stabilization), with quantitative fold-change phenotypes. (Published Jan 2024) (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 3-4)
4. Updated isoform localization summary and activation schematic: a 2024 review distills isoform-biased nuclear localization and upstream kinase mechanisms (LKB1/CAMKK2), and provides a conceptual framework via curated mouse mutant models. (Published Aug 2024) (ashraf2024finetuningampkin pages 2-2, ashraf2024finetuningampkin media b6222dde)

6) Current applications and real-world implementations

6.1 Pharmacologic modulation: metformin, AICAR and translational logic

AMPK is widely targeted pharmacologically (directly or indirectly) in metabolic and cardiovascular contexts.
- Experimental activation (AICAR): AICAR is used as an AMP mimetic to activate AMPK pools and drive mTORC1 inhibition under severe stress; mechanistic dependencies (e.g., on AXIN in some contexts) were tested in 2023 work. (li2023hierarchicalinhibitionof pages 3-4)
- Clinical/real-world drug linkage (metformin): While metformin has multiple mechanisms, a 2024 cardiotoxicity study identifies AMPK pathway restoration by metformin as protective in a drug-induced cardiotoxicity model, consistent with clinical interest in AMPK modulation for cardiometabolic protection. (rakoubian2025isoformspecificrolesof pages 2-3)

6.2 Cardiovascular/vascular implementation space

A 2024 endothelial-focused review frames AMPK as mechanosensitive (responsive to shear stress) and positions pharmacologic targeting of AMPK as a promising strategy in cardiovascular disease contexts such as atherosclerosis/ischemic injury, reflecting ongoing translational interest. (Published May 2024) (hauger2024shearstressinducedampactivated pages 2-4)

7) Expert opinions and analysis (authoritative perspectives)

A 2024 review on AMPK point-mutant mouse models emphasizes that AMPK controls diverse outcomes by phosphorylating many substrates, and that in vivo dissection of these substrate relationships remains an active area—supporting the interpretation that isoform, compartment, and substrate context determine physiological output. (ashraf2024finetuningampkin pages 2-2)

A 2024 vascular review similarly emphasizes AMPK as a central node linking mechanical cues to metabolic adaptations and disease modulation, aligning with a broad expert consensus that AMPK signaling is not purely “metabolic,” but integrates stress signals (mechanical, nutrient, calcium) into multi-system physiology. (hauger2024shearstressinducedampactivated pages 2-4)

8) Relevant recent statistics/data highlights (2023–2024)

  • ~2-fold increase in blood BHB after 48 h fasting in skeletal muscle-specific AMPKα2 knockout mice (AMPKα2ΔMusc) (n ≈ 5–7). (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 3-4)
  • ~1.5–1.6-fold increase in blood BHB after 48 h fasting in AMPKα2ΔMyo mice, and slower BHB clearance in tolerance tests, indicating impaired ketone utilization. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 3-4)

These quantitative findings are among the most direct isoform-specific physiological readouts in the retrieved 2023–2024 primary literature set and should be prioritized for functional annotation. (zhang2024ampkα2regulatesfastinginduced pages 1-2)

9) Summary functional annotation (rat Prkaa2 / AMPKα2)

Prkaa2 encodes AMPKα2, a catalytic Ser/Thr protein kinase subunit within AMPK that is activated by Thr172 phosphorylation (primarily via LKB1 and alternatively CaMKKβ/CAMKK2) and by adenine nucleotide sensing. AMPKα2 functions across cytosol–nucleus (isoform-biased nuclear shuttling) and participates in organelle-centered nutrient sensing (lysosome-associated control of mTORC1). Functionally, AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy; recent primary evidence further supports a specific role in skeletal muscle ketone utilization through stabilization of the ketolysis enzyme SCOT. (rakoubian2025isoformspecificrolesof pages 1-2, ashraf2024finetuningampkin pages 2-2, zhang2024ampkα2regulatesfastinginduced pages 1-2, li2023hierarchicalinhibitionof pages 3-4)

10) Evidence map table

Aspect Key points Evidence (citation IDs) Year/Source (short)
Molecular function Prkaa2 encodes AMPKα2, the catalytic α2 subunit of the heterotrimeric AMPK Ser/Thr kinase. AMPKα2 phosphorylates metabolic targets including ACC/ACAC (canonical readout; ACC Ser79 commonly used), HMGCR, and autophagy regulators such as ULK1; recent reviews also note mitochondrial fission target MFF Ser172. Overall role is to suppress anabolic metabolism and promote catabolic, ATP-restoring pathways. (feng2025theroleof pages 2-3, rakoubian2025isoformspecificrolesof pages 2-3, mohanty2025rethinkingampka pages 1-2) 2025 Feng review; 2025 Rakoubian review; 2025 Mohanty review
Activation and regulation Core activation is phosphorylation of AMPKα2 at Thr172 by upstream kinases, especially LKB1; CaMKKβ/CAMKK2 provides a Ca2+-responsive route. AMP/ADP binding to γ promotes allostery, favors Thr172 phosphorylation, and protects from dephosphorylation. AXIN-LKB1 lysosomal signaling helps couple glucose starvation to AMPK-dependent mTORC1 inhibition; ADaM-site ligands stabilize AMPK and protect Thr172. (rakoubian2025isoformspecificrolesof pages 1-2, ashraf2024finetuningampkin pages 2-2, rakoubian2025isoformspecificrolesof pages 2-3, li2023hierarchicalinhibitionof pages 3-4, ashraf2024finetuningampkin media b6222dde) 2025 Rakoubian review; 2024 Ashraf review; 2023 Li primary; 2024 figure summary
Localization AMPKα2 shows isoform-biased nuclear localization/shuttling, whereas α1 is mainly cytosolic. Reviews summarize that α2 contains a nuclear localization signal and can shuttle to the nucleus; α1 carries a nuclear export sequence. In heart, α2 is described as present in both cytosol and nucleus and enriched in cardiomyocytes. (feng2025theroleof pages 2-3, rakoubian2025isoformspecificrolesof pages 8-9, ashraf2024finetuningampkin pages 2-2, ashraf2024finetuningampkin media d3d7e38d) 2025 Feng review; 2025 Rakoubian review; 2024 Ashraf review/figure context
Isoform-specific role: ketone metabolism A 2024 primary study identified a specific AMPKα2 role in skeletal-muscle ketone utilization: fasting AMPKα2ΔMusc mice showed ~2-fold higher blood BHB, and AMPKα2ΔMyo mice ~1.5–1.6-fold higher blood BHB after 48 h fasting versus WT; AMPKα2 loss slowed BHB clearance. Mechanistically, AMPKα2 binds and stabilizes SCOT, limiting SCOT ubiquitination/degradation. (zhang2024ampkα2regulatesfastinginduced pages 1-2, zhang2024ampkα2regulatesfastinginduced pages 3-4, zhang2024ampkα2regulatesfastinginduced pages 2-3, zhang2024ampkα2regulatesfastinginduced pages 5-6) 2024 Zhang et al., Scientific Reports
Isoform specificity and tissue distribution α2 is preferentially enriched in skeletal muscle, cardiac muscle, and liver and can be more AMP responsive than α1. In heart, α2 is the predominant catalytic isoform and α1 does not fully compensate for α2 loss in stress adaptation. (kim2025thelinkbetween pages 5-7, rakoubian2025isoformspecificrolesof pages 8-9, ashraf2024finetuningampkin pages 2-2) 2025 Kim review; 2025 Rakoubian review; 2024 Ashraf review
Pathways/processes Major downstream processes include inhibition of mTORC1, activation of autophagy/mitophagy, stimulation of mitochondrial adaptation/biogenesis, and broad metabolic reprogramming during nutrient stress and exercise. (rakoubian2025isoformspecificrolesof pages 2-3, malik2025theampkpathway pages 3-4, jang2023thrap3promotesnonalcoholic pages 1-2) 2025 Rakoubian review; 2025 Malik review; 2023 Jang primary
Example context: NAFLD In NAFLD models, Thrap3 suppresses AMPK-mediated autophagy; liver Thrap3 knockout enhanced cytosolic translocation of AMPK from the nucleus, increased AMPK activation, improved mitochondrial function, and reduced lipid accumulation, supporting therapeutic interest in restoring AMPK signaling. (jang2023thrap3promotesnonalcoholic pages 1-2) 2023 Jang et al., Exp Mol Med
Example context: cardiotoxicity In a 2024 cardiotoxicity study, impaired PRKAA/AMPK signaling contributed to defective autophagosome-lysosome fusion during crizotinib injury; metformin restored AMPK-related signaling and rescued cardiomyocyte/cardiac injury phenotypes. ACC Ser79 phosphorylation was used as a PRKAA target readout. (rakoubian2025isoformspecificrolesof pages 2-3) 2024 Xu et al., Autophagy
Example context: endothelial shear stress / vascular biology Recent vascular review literature describes AMPK, including PRKAA2/AMPKα2, as a mechanosensitive endothelial regulator linking laminar shear stress to metabolic adaptation and vascular protection; it is discussed as a therapeutic target in cardiovascular disease. (hauger2024shearstressinducedampactivated pages 2-4) 2024 Hauger & Hordijk review

Table: This table summarizes the core functional annotation of rat Prkaa2/AMPKα2, including molecular activity, activation mechanisms, localization, isoform-specific phenotypes, and representative disease contexts. It is useful as a compact evidence map tying recent literature to functional interpretation.

11) Key cited sources with URLs and publication dates (from retrieved corpus)

  • Li M. et al. “Hierarchical inhibition of mTORC1 by glucose starvation-triggered AXIN lysosomal translocation and by AMPK.” Life Metabolism. Mar 2023. https://doi.org/10.1093/lifemeta/load005 (li2023hierarchicalinhibitionof pages 3-4)
  • Jang H-J. et al. “Thrap3 promotes nonalcoholic fatty liver disease by suppressing AMPK-mediated autophagy.” Experimental & Molecular Medicine. Aug 2023. https://doi.org/10.1038/s12276-023-01047-4 (jang2023thrap3promotesnonalcoholic pages 1-2)
  • Zhang L. et al. “AMPKα2 regulates fasting-induced hyperketonemia by suppressing SCOT ubiquitination and degradation.” Scientific Reports. Jan 2024. https://doi.org/10.1038/s41598-023-49991-5 (zhang2024ampkα2regulatesfastinginduced pages 1-2)
  • Hauger P.C., Hordijk P.L. “Shear Stress-Induced AMP-Activated Protein Kinase Modulation in Endothelial Cells…” Int J Mol Sci. May 2024. https://doi.org/10.3390/ijms25116047 (hauger2024shearstressinducedampactivated pages 2-4)
  • Ashraf N., Van Nostrand J.L. “Fine-tuning AMPK in physiology and disease using point-mutant mouse models.” Disease Models & Mechanisms. Aug 2024. https://doi.org/10.1242/dmm.050798 (ashraf2024finetuningampkin pages 2-2)

Limitations of this report (evidence-bound)

  • The retrieved full texts did not explicitly contain UniProt Q09137; therefore, cross-referencing to that accession is inferred via consistent gene/protein identity statements rather than directly quoted mapping. (kim2025thelinkbetween pages 5-7, ashraf2024finetuningampkin pages 2-2)
  • Several canonical substrate phosphosites (e.g., ACC Ser79; HMGCR Ser871) are referenced as concepts or readouts in the corpus, but residue-level details were not consistently present in the extracted snippets; deeper extraction from additional full texts could strengthen site-specific annotation. (mohanty2025rethinkingampka pages 1-2, li2023hierarchicalinhibitionof pages 3-4)

References

  1. (kim2025thelinkbetween pages 5-7): Sohyun Kim, Jihyun Baek, and Man S. Kim. The link between dietary timing and exercise performance through adipocyte ampkα2 signaling. International Journal of Molecular Sciences, 26:6061, Jun 2025. URL: https://doi.org/10.3390/ijms26136061, doi:10.3390/ijms26136061. This article has 4 citations.

  2. (rakoubian2025isoformspecificrolesof pages 8-9): Ani Rakoubian, Julia Khinchin, Johnathan Yarbro, Satoru Kobayashi, and Qiangrong Liang. Isoform-specific roles of amp-activated protein kinase in cardiac physiology and pathophysiology. Frontiers in Cardiovascular Medicine, Aug 2025. URL: https://doi.org/10.3389/fcvm.2025.1638515, doi:10.3389/fcvm.2025.1638515. This article has 13 citations and is from a peer-reviewed journal.

  3. (hauger2024shearstressinducedampactivated pages 2-4): Philipp C. Hauger and Peter L. Hordijk. Shear stress-induced amp-activated protein kinase modulation in endothelial cells: its role in metabolic adaptions and cardiovascular disease. International Journal of Molecular Sciences, 25:6047, May 2024. URL: https://doi.org/10.3390/ijms25116047, doi:10.3390/ijms25116047. This article has 18 citations.

  4. (ashraf2024finetuningampkin pages 2-2): Naghmana Ashraf and Jeanine L. Van Nostrand. Fine-tuning ampk in physiology and disease using point-mutant mouse models. Disease Models & Mechanisms, Aug 2024. URL: https://doi.org/10.1242/dmm.050798, doi:10.1242/dmm.050798. This article has 11 citations and is from a domain leading peer-reviewed journal.

  5. (rakoubian2025isoformspecificrolesof pages 1-2): Ani Rakoubian, Julia Khinchin, Johnathan Yarbro, Satoru Kobayashi, and Qiangrong Liang. Isoform-specific roles of amp-activated protein kinase in cardiac physiology and pathophysiology. Frontiers in Cardiovascular Medicine, Aug 2025. URL: https://doi.org/10.3389/fcvm.2025.1638515, doi:10.3389/fcvm.2025.1638515. This article has 13 citations and is from a peer-reviewed journal.

  6. (rakoubian2025isoformspecificrolesof pages 2-3): Ani Rakoubian, Julia Khinchin, Johnathan Yarbro, Satoru Kobayashi, and Qiangrong Liang. Isoform-specific roles of amp-activated protein kinase in cardiac physiology and pathophysiology. Frontiers in Cardiovascular Medicine, Aug 2025. URL: https://doi.org/10.3389/fcvm.2025.1638515, doi:10.3389/fcvm.2025.1638515. This article has 13 citations and is from a peer-reviewed journal.

  7. (mohanty2025rethinkingampka pages 1-2): Shraddha S. Mohanty, Shweta Warrier, and Annapoorni Rangarajan. Rethinking ampk: a reversible switch fortifying cancer cell stress-resilience. The Yale Journal of Biology and Medicine, 98:33-52, Mar 2025. URL: https://doi.org/10.59249/jkbb6336, doi:10.59249/jkbb6336. This article has 10 citations.

  8. (li2023hierarchicalinhibitionof pages 3-4): Mengqi Li, Xiaoyan Wei, Jinye Xiong, Jin-Wei Feng, Chen-Song Zhang, and Sheng-Cai Lin. Hierarchical inhibition of mtorc1 by glucose starvation-triggered axin lysosomal translocation and by ampk. Life Metabolism, Mar 2023. URL: https://doi.org/10.1093/lifemeta/load005, doi:10.1093/lifemeta/load005. This article has 25 citations.

  9. (ashraf2024finetuningampkin media b6222dde): Naghmana Ashraf and Jeanine L. Van Nostrand. Fine-tuning ampk in physiology and disease using point-mutant mouse models. Disease Models & Mechanisms, Aug 2024. URL: https://doi.org/10.1242/dmm.050798, doi:10.1242/dmm.050798. This article has 11 citations and is from a domain leading peer-reviewed journal.

  10. (ashraf2024finetuningampkin media d3d7e38d): Naghmana Ashraf and Jeanine L. Van Nostrand. Fine-tuning ampk in physiology and disease using point-mutant mouse models. Disease Models & Mechanisms, Aug 2024. URL: https://doi.org/10.1242/dmm.050798, doi:10.1242/dmm.050798. This article has 11 citations and is from a domain leading peer-reviewed journal.

  11. (jang2023thrap3promotesnonalcoholic pages 1-2): Hyun-Jun Jang, Yo Han Lee, Tam Dao, Yunju Jo, Keon Woo Khim, Hye-jin Eom, Ju Eun Lee, Yi Jin Song, Sun Sil Choi, Kieun Park, Haneul Ji, Young Chan Chae, Kyungjae Myung, Hongtae Kim, Dongryeol Ryu, Neung Hwa Park, Sung Ho Park, and Jang Hyun Choi. Thrap3 promotes nonalcoholic fatty liver disease by suppressing ampk-mediated autophagy. Experimental & Molecular Medicine, 55:1720-1733, Aug 2023. URL: https://doi.org/10.1038/s12276-023-01047-4, doi:10.1038/s12276-023-01047-4. This article has 21 citations and is from a peer-reviewed journal.

  12. (zhang2024ampkα2regulatesfastinginduced pages 1-2): Lingxue Zhang, Yanqiao Lu, Junqing An, Yin Wu, Zhixue Liu, and Ming-Hui Zou. Ampkα2 regulates fasting-induced hyperketonemia by suppressing scot ubiquitination and degradation. Scientific Reports, Jan 2024. URL: https://doi.org/10.1038/s41598-023-49991-5, doi:10.1038/s41598-023-49991-5. This article has 6 citations and is from a peer-reviewed journal.

  13. (zhang2024ampkα2regulatesfastinginduced pages 2-3): Lingxue Zhang, Yanqiao Lu, Junqing An, Yin Wu, Zhixue Liu, and Ming-Hui Zou. Ampkα2 regulates fasting-induced hyperketonemia by suppressing scot ubiquitination and degradation. Scientific Reports, Jan 2024. URL: https://doi.org/10.1038/s41598-023-49991-5, doi:10.1038/s41598-023-49991-5. This article has 6 citations and is from a peer-reviewed journal.

  14. (zhang2024ampkα2regulatesfastinginduced pages 3-4): Lingxue Zhang, Yanqiao Lu, Junqing An, Yin Wu, Zhixue Liu, and Ming-Hui Zou. Ampkα2 regulates fasting-induced hyperketonemia by suppressing scot ubiquitination and degradation. Scientific Reports, Jan 2024. URL: https://doi.org/10.1038/s41598-023-49991-5, doi:10.1038/s41598-023-49991-5. This article has 6 citations and is from a peer-reviewed journal.

  15. (zhang2024ampkα2regulatesfastinginduced pages 5-6): Lingxue Zhang, Yanqiao Lu, Junqing An, Yin Wu, Zhixue Liu, and Ming-Hui Zou. Ampkα2 regulates fasting-induced hyperketonemia by suppressing scot ubiquitination and degradation. Scientific Reports, Jan 2024. URL: https://doi.org/10.1038/s41598-023-49991-5, doi:10.1038/s41598-023-49991-5. This article has 6 citations and is from a peer-reviewed journal.

  16. (feng2025theroleof pages 2-3): Yue Feng, Zixiong Zhu, Yubin He, and Xuewen Li. The role of ampkα in the mechanism of development and treatment of heart failure. Reviews in Cardiovascular Medicine, Aug 2025. URL: https://doi.org/10.31083/rcm36391, doi:10.31083/rcm36391. This article has 5 citations and is from a peer-reviewed journal.

  17. (malik2025theampkpathway pages 3-4): Nazma Malik and R. Shaw. The ampk pathway: molecular rejuvenation of metabolism and mitochondria. Annual review of cell and developmental biology, Aug 2025. URL: https://doi.org/10.1146/annurev-cellbio-120420-094431, doi:10.1146/annurev-cellbio-120420-094431. This article has 29 citations and is from a domain leading peer-reviewed journal.

Artifacts

Citations

  1. mohanty2025rethinkingampka pages 1-2
  2. li2023hierarchicalinhibitionof pages 3-4
  3. ashraf2024finetuningampkin pages 2-2
  4. rakoubian2025isoformspecificrolesof pages 8-9
  5. rakoubian2025isoformspecificrolesof pages 2-3
  6. hauger2024shearstressinducedampactivated pages 2-4
  7. kim2025thelinkbetween pages 5-7
  8. rakoubian2025isoformspecificrolesof pages 1-2
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  10. malik2025theampkpathway pages 3-4
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Deep Research Report: Prkaa2 (rat)

(Prkaa2-deep-research.md)

Deep Research Report: Prkaa2 (rat)

Generated using OpenAI Deep Research API

Prkaa2 Gene (Rattus norvegicus) – Comprehensive Functional Annotation Report

Gene Function and Molecular Mechanisms

Prkaa2 encodes the AMP-activated protein kinase (AMPK) catalytic α2 subunit, a serine/threonine kinase that serves as a central energy sensor and regulator of metabolism (pmc.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). The α2 subunit, together with regulatory β and γ subunits, forms the heterotrimeric AMPK complex which is activated under conditions of low cellular energy (high AMP/ADP relative to ATP) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Activation requires phosphorylation of a critical threonine (Thr^172) in the α2 subunit’s activation loop by upstream kinases such as LKB1 or CaMKK2 (pmc.ncbi.nlm.nih.gov). Once active, AMPKα2 phosphorylates numerous downstream targets to restore energy homeostasis – for example, it inactivates acetyl-CoA carboxylase (ACC) and HMG-CoA reductase, thereby down-regulating fatty acid and cholesterol synthesis while up-regulating fatty acid oxidation (rgd.mcw.edu) (rgd.mcw.edu). It also phosphorylates proteins like TSC2 and Raptor to inhibit mTORC1 signaling, conserving energy under stress (rgd.mcw.edu). Notably, AMPKα2 can directly modulate nuclear processes: a landmark study showed it associates with chromatin and phosphorylates histone H2B at Ser36, activating stress-response gene transcription (www.ncbi.nlm.nih.gov). In summary, Prkaa2’s product functions as a catalytic kinase subunit with “AMP-activated protein kinase activity”, binding ATP and magnesium (as a typical protein serine/threonine kinase) (rgd.mcw.edu), and acting as a molecular switch that shifts cells from energy-consuming processes to energy-producing pathways during metabolic stress (pmc.ncbi.nlm.nih.gov) (rgd.mcw.edu).

Cellular Localization and Complex Composition

The AMPKα2 protein is predominantly a cytosolic kinase, but it dynamically localizes to multiple cellular compartments. It resides in the “nucleotide-activated protein kinase complex” (AMPK heterotrimer) within the cytoplasm and can translocate to the nucleus upon activation (rgd.mcw.edu) (pubmed.ncbi.nlm.nih.gov). In fact, complexes containing the α2 isoform show a tendency for nuclear localization and greater AMP-dependence compared to α1-containing complexes (pubmed.ncbi.nlm.nih.gov). Activated AMPKα2 has been observed in the nucleoplasm and even at nuclear speckles, consistent with its role in regulating transcription and chromatin remodeling (rgd.mcw.edu). Prkaa2 is also found at specialized subcellular sites: the protein has been detected in neuronal cell bodies and dendrites (www.ncbi.nlm.nih.gov), and at the apical plasma membrane in polarized cells (www.ncbi.nlm.nih.gov). Recent studies highlight that AMPK complexes can localize to organelle surfaces – for example, AMPK is recruited to lysosomal membranes during glucose starvation, where a scaffold (AXIN-LKB1) facilitates AMPKα2 phosphorylation and activation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Thus, AMPKα2’s localization is both cytoplasmic and nuclear, with additional compartment-specific tethering (lysosome, endoplasmic reticulum, etc.) to fine-tune its signaling in response to cellular stress (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These localization properties enable AMPKα2 to access substrates throughout the cell, from metabolic enzymes in the cytosol to transcriptional regulators in the nucleus.

Biological Processes and Pathway Involvement

Prkaa2 (AMPKα2) is a master regulator in numerous biological processes related to energy balance and metabolism. A primary role is maintaining energy homeostasis at both cellular and whole-organism levels (rgd.mcw.edu) (pmc.ncbi.nlm.nih.gov). When activated by rising AMP/ADP, AMPKα2 triggers catabolic pathways that generate ATP and suppresses anabolic pathways that consume ATP (pmc.ncbi.nlm.nih.gov). For example, AMPKα2 positively regulates glucose uptake and glycolysis (enhancing ATP production) (rgd.mcw.edu) (rgd.mcw.edu), and it stimulates fatty acid oxidation while inhibiting fatty acid and lipid biosynthesis (rgd.mcw.edu). It also acutely inhibits cholesterol synthesis via phosphorylation of HMG-CoA reductase (rgd.mcw.edu). These actions translate to higher-order processes like glucose homeostasis and lipid homeostasis in tissues (rgd.mcw.edu) (rgd.mcw.edu). AMPKα2 is a key upstream regulator of autophagy – energy stress causes AMPKα2 to activate autophagy pathways (e.g. via ULK1 phosphorylation), promoting recycling of nutrients (rgd.mcw.edu) (rgd.mcw.edu). Concurrently, it negatively regulates growth and proliferative signals: AMPKα2 inhibits the TORC1 (mTOR) signaling pathway under low energy, restraining protein synthesis and cell growth (rgd.mcw.edu). AMPKα2 activation can also protect against apoptosis during mild stress, evidenced by its role in the negative regulation of apoptotic processes and promotion of cell survival pathways (rgd.mcw.edu). Additionally, Prkaa2 is involved in cellular stress responses to various stimuli – it participates in the response to glucose starvation, nutrient deprivation, oxidative stress, calcium influx, and even xenobiotic exposure (rgd.mcw.edu) (rgd.mcw.edu). Intriguingly, AMPKα2 has been implicated in regulating circadian rhythm and gene expression, linking metabolic state to the circadian clock and transcriptional programs (rgd.mcw.edu) (rgd.mcw.edu). Overall, through the AMPKα2 subunit, Prkaa2 influences a broad network of biological pathways including the AMPK signaling pathway, insulin signaling, mTOR signaling, and pathways governing lipid metabolism and autophagy (rgd.mcw.edu). This breadth of action underscores AMPKα2’s central role in balancing anabolic and catabolic processes across diverse contexts.

Disease Associations and Phenotypes

Given its central metabolic role, dysregulation of Prkaa2/AMPKα2 is linked to multiple diseases and phenotypic outcomes. In rodent models, loss or inhibition of AMPKα2 leads to metabolic disturbances: AMPKα2-knockout mice exhibit glucose intolerance and insulin resistance, demonstrating the subunit’s importance in whole-body insulin sensitivity (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Specifically, AMPKα2–/– mice have elevated blood glucose and impaired muscle glucose uptake and glycogen synthesis under insulin stimulation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This phenotype is accompanied by low plasma insulin and increased catecholamine levels, suggesting that AMPKα2 helps restrain sympathetic output to promote insulin secretion and action (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Consistent with these findings, the human ortholog PRKAA2 has been implicated in type 2 diabetes mellitus susceptibility (www.ncbi.nlm.nih.gov). Polymorphisms in human PRKAA2 associate with risk of type 2 diabetes and with altered blood lipid profiles, linking this gene to metabolic syndrome traits (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

AMPKα2 also has a significant role in cardiovascular health. It is highly expressed in cardiac muscle, where it safeguards energy balance in the heart. Experimental studies indicate cardioprotective effects: activation of AMPKα2 (e.g. by the antidiabetic drug metformin) can protect against heart failure or ischemic injury (rgd.mcw.edu). Conversely, dysfunction of AMPKα2 is associated with cardiac pathology – annotations link Prkaa2 to cardiomegaly, cardiomyopathy, and cardiac fibrosis phenotypes (rgd.mcw.edu). For instance, reduced AMPKα2 activity may contribute to pathological cardiac hypertrophy and fibrotic remodeling, while active AMPKα2 helps maintain cardiac energetics and contractile function (as suggested by improved outcomes with AMPK-activating treatments) (rgd.mcw.edu) (rgd.mcw.edu). In the nervous system, Prkaa2 is expressed in brain neurons and may influence neuronal survival and plasticity during metabolic stress. While severe overactivation of AMPK in neurons can be deleterious (e.g. during ischemia), moderate AMPKα2 activity is thought to support neuronal health during nutrient stress via autophagy induction and metabolic support (rgd.mcw.edu) (www.ncbi.nlm.nih.gov). However, the exact neurological phenotypes require further elucidation.

Importantly, Prkaa2’s involvement in disease is often context-dependent. Its proper function appears to protect against metabolic diseases (diabetes, fatty liver) and cardiovascular diseases, whereas loss of function or improper regulation predisposes to these conditions. Thus, AMPKα2 is viewed as a potential therapeutic target – for example, pharmacological AMPK activators (AICAR, metformin, ALA, etc.) improve metabolic parameters and are being explored for treating insulin resistance and cardiometabolic disorders (rgd.mcw.edu) (rgd.mcw.edu).

Protein Domains and Structural Features

The AMPKα2 protein (enzyme commission number EC 2.7.11.31) is approximately 552 amino acids in length and contains several well-defined domains critical for its activity and regulation. At the N-terminus (~residues 1–270) is the serine/threonine kinase domain, which includes the ATP-binding pocket and the activation loop harboring Thr^172 (whose phosphorylation is required for kinase activation) (pmc.ncbi.nlm.nih.gov). This kinase domain conforms to the typical bilobal architecture of protein kinases and binds Mg^2+-ATP, consistent with the enzyme’s ATP binding and metal ion binding activities (rgd.mcw.edu). Following the catalytic domain, the α2 subunit harbors an auto-inhibitory domain (AID) – a segment that can fold back onto the kinase domain to dampen its activity under resting conditions. The AID (identified in AMPKα1 around residues 313–335 and conserved in α2) interacts with the kinase domain and must be disengaged for full activation (pmc.ncbi.nlm.nih.gov). Binding of AMP/ADP to the γ subunit and phosphorylation of Thr^172 both serve to relieve this autoinhibition, prompting a conformational change that activates the kinase (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

The C-terminal region (~residues 331–552) of AMPKα2 is crucial for forming the heterotrimeric complex. It contains a protein-interaction domain that binds the β subunit and, indirectly, the γ subunit, thereby assembling the stable αβγ complex (pmc.ncbi.nlm.nih.gov). Within this region, specific motifs have been identified, such as the α-Subunit Carboxy-terminal Domain (α-CTD) and α-regulatory subunit interacting motif (α-RIM), which contact the γ subunit and mediate the allosteric effects of nucleotide binding (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The β subunit-binding segment of α2 helps tether a β subunit (which itself contains a glycogen-binding domain) – this association can target AMPK to glycogen particles and other cellular structures. Notably, the α2 subunit’s complex with β and γ subunits is sometimes termed a “nucleotide-activated protein kinase complex”, highlighting that AMP/ADP binding to γ subunits regulates the whole complex’s conformation and activity (rgd.mcw.edu). No transmembrane region is present in AMPKα2 (it is a soluble protein), but the complex can associate with membranes via adaptor proteins or by virtue of the β subunit’s myristoylation. In summary, AMPKα2’s domain architecture – kinase domain, autoinhibitory linker, and C-terminal subunit interaction domains – is designed for tight regulation, ensuring the kinase is only active when appropriate (i.e. low energy) and properly integrated into the larger AMPK complex.

Expression Patterns and Regulation

Expression of Prkaa2 is widespread in rat tissues but shows higher levels in organs with high energy turnover. RNA expression data indicate biased expression in skeletal muscle and heart, which have among the highest Prkaa2 mRNA levels (for example, skeletal muscle shows the highest RPKM ~915, and heart ~626) (www.ncbi.nlm.nih.gov). This corresponds to protein data showing abundant AMPKα2 in striated muscle (both skeletal and cardiac), reflecting these tissues’ reliance on AMPK for metabolic control during contraction or exercise. Prkaa2 is also significantly expressed in the brain, including regions like the hippocampus and cortex (www.mousephenotype.org) (www.mousephenotype.org), and in metabolically active tissues such as the liver, kidney, and adipose tissue (though in adipose AMPKα1 may be relatively more expressed). In the central nervous system, both neurons and glial cells express AMPKα2; notably, it is present in neuron cell bodies and dendrites (www.ncbi.nlm.nih.gov). Lower but appreciable expression is found in lung, spleen, and testes, indicating a fairly ubiquitous presence consistent with a fundamental cellular role. The AMPKα1 (Prkaa1) isoform is co-expressed in many tissues, often at higher levels in liver and adipose, whereas α2 is predominant in muscle and perhaps neuron-rich areas (pmc.ncbi.nlm.nih.gov).

Regulation of expression: Prkaa2 transcription and protein levels can be modulated by dietary and hormonal signals. For instance, chronic energy surplus or deficit can alter AMPK levels – rodent studies show that exercise training or chronic leptin treatment increases AMPKα2 expression and phosphorylation in muscle (rgd.mcw.edu), potentially as an adaptive response to enhanced fatty acid oxidation demand. Fasting and caloric restriction tend to elevate AMPK activity (through post-translational mechanisms) rather than dramatically changing expression, while high-fat feeding and obesity may reduce AMPKα2 activity (sometimes via reduced expression or increased inhibitory phosphorylation by insulin signaling). Certain AMPK activators (AICAR, metformin) don’t necessarily change AMPKα2 expression but strongly increase its activation state (phospho-Thr^172 levels) (rgd.mcw.edu) (rgd.mcw.edu). Conversely, insulin and high glucose can suppress AMPK activation; insulin signaling leads to Akt-mediated phosphorylation of AMPKα (at Ser485/491 in α1/α2) which can dampen Thr^172 phosphorylation. Stress conditions (hypoxia, ischemia) can elevate AMPKα2 activation; for example, in cardiac ischemia, AMPKα2 is rapidly activated to help ATP generation. On a developmental note, Prkaa2 expression is detectable in embryonic tissues and increases postnatally in heart and muscle as energy demands rise. Additionally, circadian regulators may influence Prkaa2 expression or activity rhythmically, aligning metabolic enzyme oscillations with day-night cycles (rgd.mcw.edu). Overall, Prkaa2 is constitutively expressed in most cell types, with post-translational regulation (AMP/ATP ratio, upstream kinases) being the dominant mode of controlling AMPKα2 activity, though gene expression can be upregulated by chronic metabolic challenges or endurance training.

Evolutionary Conservation

The AMPKα2 protein is highly conserved across eukaryotic evolution, underscoring its fundamental role in cellular physiology. Prkaa2 belongs to the SNF1/AMPK family of protein kinases, which first appeared in single-celled eukaryotes. The canonical energy-sensing kinase in budding yeast, SNF1, is an ortholog of AMPKα – it likewise forms a heterotrimer (Snf1 catalytic with Snf4 regulatory subunit) and responds to nutrient stress, indicating a common ancestral energy-sensing mechanism (pmc.ncbi.nlm.nih.gov). In mammals, AMPKα2 and its isoform α1 are ~90% identical in the kinase domain and both perform the energy-monitor role, having arisen from gene duplication. Across species, the amino acid sequence of AMPKα2 is strongly conserved: the rat AMPKα2 protein shares ~99% identity with mouse AMPKα2 (reflecting only a few residue differences) and high identity with the human AMPKα2 (PRKAA2) protein (approximately 96–98% identity, with almost all differences in non-critical regions). Key functional motifs – such as the ATP-binding pocket, the activation loop (Thr^172 site), the AID region, and subunit interaction surfaces – are essentially invariant from rodents to humans, highlighting strong purifying selection due to the protein’s vital function (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Even in more distant organisms like Drosophila or C. elegans, the AMPKα catalytic subunit is easily recognizable and can substitute functionally in cross-species experiments, demonstrating conservation of function. The regulatory network is also conserved – the upstream kinase LKB1 and canonical downstream targets (ACC, etc.) exist in all mammals and many metazoans. This evolutionary conservation extends to the GO annotations: for example, “AMP-activated protein kinase activity” and “cellular response to glucose starvation” are attributed to orthologs from yeast (SNF1) through plants (SnRK1 in Arabidopsis) to animals (rgd.mcw.edu). The ancient origin and conservation of Prkaa2’s function emphasize that the ability to sense energy status and adjust metabolism is a fundamental necessity across life.

Key Experimental Evidence and Literature

Numerous studies have elucidated the function of Prkaa2/AMPKα2 through a combination of genetic, biochemical, and physiological approaches:

  • Gene Knockout Studies: Viollet et al. (2003) generated AMPKα2-knockout mice, revealing that AMPKα2–null animals develop impaired glucose tolerance and insulin resistance, especially under metabolic challenge (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Despite normal muscle AMPKα1, these mice had high fed-state blood glucose and reduced insulin-stimulated glucose disposal, pinpointing AMPKα2’s non-redundant role in maintaining insulin sensitivity in vivo (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This study underscored AMPKα2 as crucial for whole-body metabolic homeostasis.

  • Enzymatic Activity and Substrates: Foundational biochemical work by Woods, Hardie, Carling, and colleagues characterized AMPK isoforms. Woods et al. (1996) and Salt et al. (1998) showed that AMPK complexes containing the α2 subunit are more sensitive to AMP and may localize to the nucleus preferentially (pubmed.ncbi.nlm.nih.gov). These studies, isolating α1- vs α2-containing complexes, also noted subtle differences in substrate specificity (pubmed.ncbi.nlm.nih.gov). Direct targets of AMPKα2 were identified: for example, Park et al. (2002) demonstrated in rats that exercise activates AMPKα2, leading to phosphorylation of ACC and HMG-CoA reductase in muscle and liver, thereby acutely regulating fatty acid and cholesterol metabolism (rgd.mcw.edu). This provided molecular evidence for AMPKα2’s role in fuel utilization during exercise.

  • Metabolic Regulation in Muscle: Sakoda et al. (2002) showed that AICAR (an AMP mimetic) increases glucose uptake in skeletal muscle in an AMPK-dependent manner (rgd.mcw.edu). In their experiments, muscle from rats required functional AMPK (particularly α2 in muscle) for AICAR to stimulate glucose transport, whereas adipocytes did not, highlighting tissue-specific roles of AMPKα2 in glucose metabolism. Steinberg et al. (2003) reported that chronic leptin treatment in rodents elevated AMPKα2 activity in muscle, linking hormonal signals to AMPK activation (rgd.mcw.edu).

  • Nuclear Functions: A seminal discovery by Bungard et al. (2010) revealed a novel nuclear role for AMPKα2: under stress, AMPKα2 translocates to nuclei and phosphorylates histone H2B on Ser36, directly enhancing transcription of stress-response genes (www.ncbi.nlm.nih.gov). This was evidenced by chromatin immunoprecipitation and loss-of-function mutants of H2B S36, demonstrating that this histone mark is required for full transcriptional activation and cell survival during metabolic stress (www.ncbi.nlm.nih.gov). This finding expanded AMPKα2’s functional repertoire beyond metabolism into gene regulation and established a mechanism for how energy stress signals reach the genome.

  • Cardiac Studies: Research in cardiomyocytes and in vivo hearts (e.g., Tzanavari et al. 2016) showed that pharmacological activation of AMPKα2 (by metformin) protects against sepsis-induced or ischemic cardiac dysfunction (rgd.mcw.edu). Additionally, Sayed-Ahmed et al. (2019) found that preventing AMPK suppression mitigated drug-induced cardiotoxicity (rgd.mcw.edu). These studies highlight AMPKα2 as a key player in cardiac stress adaptation, aligning with GO annotations for positive regulation of autophagy and negative regulation of apoptosis in heart tissue under stress (rgd.mcw.edu) (rgd.mcw.edu).

  • Structural and Mechanistic Insights: High-resolution crystal structures of AMPK complexes (reviewed by Yan et al. 2018) have visualized the conformational changes of AMPKα2 upon nucleotide binding. These studies confirm that binding of AMP/ADP to the γ subunit and phosphorylation of Thr^172 stabilize the kinase domain in an active conformation and prevent dephosphorylation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Mutagenesis of the autoinhibitory region and α-RIM motifs in AMPKα2 corroborated their roles in sensing AMP and relieving autoinhibition (pmc.ncbi.nlm.nih.gov). Thus, structural biology combined with mutational analyses have provided a molecular basis for GO terms such as “AMP-activated protein kinase activity” and “protein autoinhibition”.

Each of these key experiments has contributed to the understanding captured in Gene Ontology annotations. From molecular function (e.g. “AMP-activated protein kinase activity” (rgd.mcw.edu), “ATP binding” (rgd.mcw.edu)) to biological processes (“fatty acid homeostasis” (www.ncbi.nlm.nih.gov), “response to glucose starvation” (rgd.mcw.edu), “negative regulation of TORC1 signaling” (rgd.mcw.edu), etc.) and cellular components (“AMPK complex” (rgd.mcw.edu), “nucleus” (rgd.mcw.edu), “apical plasma membrane” (www.ncbi.nlm.nih.gov)), the research evidence solidly supports Prkaa2’s multi-faceted role in the cell. This makes Prkaa2 (AMPKα2) a crucial gene for which GO curation captures a wide spectrum of functions – from metabolic enzyme phosphorylation to chromatin modulation – all converging on the theme of energy-sensing and adaptive response.

References: The information above is drawn from a synthesis of literature and databases, including gene/protein databases and key publications (e.g., Hardie DG and colleagues’ work on AMPK, Viollet et al. on knockout phenotypes, and recent molecular studies), as cited in-line. The report provides a foundation for GO annotation by tying specific experimental evidence to GO terms in Gene Ontology for Prkaa2. Each citation (e.g., (www.ncbi.nlm.nih.gov)) corresponds to published data supporting the statement, ensuring that GO curators have source material for each functional aspect described.

📚 Additional Documentation

Notes

(Prkaa2-notes.md)

PRKAA2 Research Notes

Key Research Findings

Core Catalytic Function

PRKAA2 encodes the α2 catalytic subunit of AMPK, which has intrinsic serine/threonine kinase activity. The α2 isoform differs from α1 in tissue distribution and substrate specificity PMID:8955377.

Direct Substrates with Strong Evidence

  1. ACC (Acetyl-CoA Carboxylase): Direct phosphorylation inhibits fatty acid synthesis PMID:12065578.

  2. PFK-2 (6-Phosphofructo-2-kinase): Direct phosphorylation at Ser466 activates the enzyme, promoting glycolysis during energy stress PMID:11069105.

  3. ChREBP: Direct phosphorylation at Ser568 inhibits DNA binding, preventing lipogenic gene expression PMID:11724780.

Tissue-Specific Expression Patterns

  • Liver: Highly expressed, critical for hepatic metabolism
  • Skeletal Muscle: Essential for exercise-induced metabolic changes
  • Heart: Critical during ischemic stress
  • Adipose Tissue: Responds to adrenergic stimulation PMID:17253964
  • Brain: Specialized functions in neurons, recently discovered role in photoreceptors

Recent Paradigm Shifts (2024)

Autophagy Regulation Controversy

Traditional view: AMPK → inhibits mTOR → activates autophagy
New evidence: AMPK may actually suppress autophagy under certain conditions, particularly amino acid starvation. This represents a major shift in understanding [Web search findings 2024].

Neuronal Specialization

2024 research identified PRKAA2-specific functions in photoreceptor neurons involving IMPDH (inosine monophosphate dehydrogenase) regulation, representing novel therapeutic targets.

Energy Sensing Mechanisms

AMPK α2 responds to:
1. AMP:ATP ratio changes: Primary activation mechanism
2. Upstream kinases: LKB1 complex PMID:14511394
3. Calcium signaling: [PMID:25788287 studies show calcium-dependent activation]
4. Pharmacological activators: Caffeine PMID:19608206, AICAR, metformin

Complex Assembly

AMPK functions as a heterotrimeric complex:
- α subunit (catalytic): PRKAA1 or PRKAA2
- β subunit (regulatory): bridges α and γ subunits PMID:15695819
- γ subunit (regulatory): contains CBS domains for AMP/ATP binding

Metabolic Integration Points

  1. Fatty Acid Homeostasis: Inhibits synthesis (via ACC), promotes oxidation
  2. Glucose Homeostasis: Context-dependent effects on glycolysis vs gluconeogenesis
  3. Cholesterol Homeostasis: Inhibits HMGCR, reducing cholesterol synthesis
  4. Energy Homeostasis: Master coordinator of anabolic vs catabolic balance

Annotations Requiring Careful Review

Strong Evidence (Accept):
- Kinase activities (AMP-activated, serine/threonine)
- ATP/nucleotide binding
- Fatty acid metabolic processes
- Energy homeostasis
- Glucose homeostasis

Context-Dependent (Mark as Non-Core):
- Autophagy regulation (complex, bidirectional)
- Circadian rhythm regulation
- Cellular responses to specific stimuli

Likely Over-Annotations (Consider Removal):
- Chromatin remodeling (likely indirect)
- Wnt signaling (likely indirect)
- Steroid biosynthesis (should be "negative regulation")
- Histone H2BS36 kinase activity (overly specific without strong rat evidence)

Future Research Directions

  1. Isoform-Specific Functions: Better understanding α1 vs α2 specialization
  2. Tissue-Specific Mechanisms: Detailed mechanisms in brain, heart, liver
  3. Therapeutic Targets: IMPDH inhibition for photoreceptor disorders
  4. Autophagy Paradox: Resolving conflicting evidence about AMPK's role in autophagy

Methodology Notes

This analysis synthesized:
- Experimental papers cited in existing GO annotations
- Recent literature (2020-2024) from web searches
- Established reviews and comprehensive studies
- Tissue-specific functional studies

Evidence Quality Assessment:
- Direct biochemical evidence > Genetic evidence > Computational predictions
- In vivo studies > In vitro studies > Cell culture
- Multiple independent studies > Single study findings

2025-01-14 - Annotation Retirement Fix

Issue: Validation failure due to 25 annotations with GO_REF:0000096 reference that no longer exist in the current GOA file.

Root Cause: The reference GO_REF:0000096 ("Automated transfer of experimentally-verified manual GO annotation data to mouse-rat orthologs") has been retired from the GOA annotation pipeline and replaced with other reference systems like GO_REF:0000121.

Action Taken: Marked all 27 annotations with original_reference_id: GO_REF:0000096 as retired: true to exclude them from GOA validation while preserving the annotation review work.

Annotations Affected: All annotations with ISO evidence type using GO_REF:0000096, including:
- GO:0031669 (cellular response to nutrient levels)
- GO:0004679 (AMP-activated protein kinase activity)
- GO:0004674 (protein serine/threonine kinase activity)
- GO:0140823 (histone H2BS36 kinase activity)
- GO:0042149 (cellular response to glucose starvation)
- Multiple other metabolic and regulatory terms

Validation Status: After marking these annotations as retired, the gene should pass GOA validation checks since retired annotations are now excluded from validation.

Note: These annotations represent legitimate functional information that was previously transferred from experimentally verified mouse/human data. The retirement only reflects changes in the GOA annotation pipeline, not changes in the underlying biology.

Bioreason Rl Predictions

(Prkaa2-bioreason-rl-predictions.md)

BioReason Chat Export

Exported on March 22, 2026 at 12:59 AM

Organism: Rattus norvegicus

Sequence:

MAEKQKHDGRVKIGHYVLGDTLGVGTFGKVKIGEHQLTGHKVAVKILNRQKIRSLDVVGKIKREIQNLKLFRHPHIIKLYQVISTPTDFFMVMEYVSGGELFDYICKHGRVEEVEARRLFQQILSAVDYCHRHMVVHRDLKPENVLLDAQMNAKIADFGLSNMMSDGEFLRTSCGSPNYAAPEVISGRLYAGPEVDIWSCGVILYALLCGTLPFDDEHVPTLFKKIRGGVFYIPEYLNRSIATLLMHMLQVDPLKRATIKDIREHEWFKQDLPSYLFPEDPSYDANVIDDEAVKEVCEKFECTESEVMNSLYSGDPQDQLAVAYHLIIDNRRIMNQASEFYLASSPPTGSFMDDMAMHIPPGLKPHPERMPPLIADSPKARCPLDALNTTKPKSLAVKKAKWHLGIRSQSKPYDIMAEVYRAMKQLDFEWKVVNAYHLRVRRKNPVTGNYVKMSLQLYLVDNRSYLLDFKSIDDEVVEQRSGSSTPQRSCSAAGLHRPRSSVDSSTAENHSLSGSLTGSLTGSTLSSASPRLGSHTMDFFEMCASLITALAR

Thinking Trace

I begin with the InterPro architecture. The N-terminal catalytic core is defined by IPR000719 (Protein kinase domain, residues 16–268) embedded within IPR011009 (Protein kinase-like domain superfamily, residues 13–269). Within this core lie IPR017441 (Protein kinase, ATP binding site, residues 22–45) and IPR008271 (Serine/threonine-protein kinase, active site, residues 135–147). This tightly clustered arrangement establishes a bilobal serine/threonine kinase engine that binds ATP and transfers phosphate to Ser/Thr residues—chemistry that directly yields GO:0005524 ATP binding and GO:0004674 protein serine/threonine kinase activity. Immediately C-terminal to the kinase core, two overlapping autoinhibitory modules—IPR028783 (PRKAA2, UBA-like autoinhibitory domain, residues 285–349) and IPR049020 (PRKAA1/2 autoinhibitory domain, residues 288–333)—precede a regulatory tail that specializes this enzyme’s behavior. This tail is characteristic of AMPK catalytic subunits and comprises IPR039148 (5'-AMP-activated protein kinase catalytic subunit alpha-2, C-terminal, residues 395–550), IPR032270 (AMPK, C-terminal adenylate sensor domain, residues 401–479), and IPR028375 (KA1 domain/Ssp2, C-terminal homologous superfamily, residues 402–552). The ordered layout—kinase core → autoinhibitory segment → adenylate-sensing and KA1-bearing C-terminus—creates an allosterically regulated kinase whose activity is tuned by adenylate nucleotides and whose C-terminal module mediates nucleic-acid/protein interactions and assembly.

This architecture causes a specific molecular function profile. The canonical kinase domain and active-site signatures specify serine/threonine phosphorylation of diverse substrates (GO:0004674), while the ATP-binding pocket supports nucleotide handling (GO:0005524). The autoinhibitory module enforces basal suppression and requires upstream phosphorylation to relieve inhibition, a hallmark of energy-sensing kinases. The adenylate sensor domain and KA1-bearing tail couple catalytic output to cellular energy status and macromolecular targeting, explaining how this kinase coordinates phosphorylation with adenylate availability.

From this molecular function, the biological process follows. An adenylate-tuned serine/threonine kinase that targets metabolic and cytoskeletal regulators will drive energy-stress signaling and metabolic remodeling. Phosphorylation of metabolic hubs and cytoskeletal elements logically feeds into energy homeostasis and cytoskeletal organization; thus the most defensible process umbrella is signal transduction feeding into energy-coupled pathways (GO:0007165 signal transduction) that modulate broader cellular economy.

Cellular location is inferred from soluble kinase architecture lacking transmembrane segments and from targeting motifs typical of AMPK catalytic subunits. The soluble catalytic fold, together with KA1/C-terminal modules that mediate chromatin and nucleic-acid interactions, supports a predominantly cytoplasmic residence with regulated access to the nucleus. This reasoning aligns with a cytoplasmic localization and accommodates dynamic nucleo-cytoplasmic shuttling (GO:0005737 cytoplasm).

Mechanistically, the kinase core is held inactive by the autoinhibitory region; activation proceeds via phosphorylation of the activation loop and subsequent assembly with adenylate-tuned regulatory partners. The C-terminal adenylate sensor and KA1 domain position the enzyme to respond to AMP/ADP levels and to dock onto macromolecular scaffolds. I therefore hypothesize that this kinase forms a heterotrimeric energy-sensing complex with regulatory subunits and nucleic-acid-associated adaptors, phosphorylating cytoskeletal and metabolic substrates to enforce energy-coupled control. Likely interaction partners include AMPK regulatory β and γ subunits that complete the energy-sensing holoenzyme, upstream activating kinases that deliver activating phosphorylation, and downstream cytoskeletal and metabolic targets that execute the program.

Functional Summary

A soluble energy-regulated serine/threonine kinase that uses an N-terminal catalytic core and a C-terminal adenylate-responsive module to phosphorylate metabolic and cytoskeletal substrates. Autoinhibitory elements restrain basal activity until relief by upstream phosphorylation and adenylate sensing. Operating primarily in the cytoplasm with regulated access to the nucleus, it coordinates energy-stress signaling and broader cellular economy by coupling nucleotide sensing to substrate phosphorylation.

UniProt Summary

Catalytic subunit of AMP-activated protein kinase (AMPK), an energy sensor protein kinase that plays a key role in energy homeostasis.

InterPro Domains

  • Protein kinase-like domain superfamily (IPR011009, homologous_superfamily) — residues 13-269
  • Protein kinase domain (IPR000719, domain) — residues 16-268
  • Protein kinase, ATP binding site (IPR017441, binding_site) — residues 22-45
  • Serine/threonine-protein kinase, active site (IPR008271, active_site) — residues 135-147
  • PRKAA2, UBA-like autoinhibitory domain (IPR028783, domain) — residues 285-349
  • PRKAA1/2, autoinhibitory domain (IPR049020, domain) — residues 288-333
  • 5'-AMP-activated protein kinase catalytic subunit alpha-2, C-terminal (IPR039148, domain) — residues 395-550
  • AMPK, C-terminal adenylate sensor domain (IPR032270, domain) — residues 401-479
  • KA1 domain/Ssp2, C-terminal (IPR028375, homologous_superfamily) — residues 402-552

GO Terms

Molecular Function: molecular_function (GO:0003674), catalytic activity (GO:0003824), binding (GO:0005488), molecular adaptor activity (GO:0060090), small molecule binding (GO:0036094), protein-macromolecule adaptor activity (GO:0030674), organic cyclic compound binding (GO:0097159), transferase activity (GO:0016740), heterocyclic compound binding (GO:1901363), protein-containing complex binding (GO:0044877), ion binding (GO:0043167), catalytic activity, acting on a protein (GO:0140096), carbohydrate derivative binding (GO:0097367), protein binding (GO:0005515), nucleoside phosphate binding (GO:1901265), protein kinase activity (GO:0004672), anion binding (GO:0043168), transferase activity, transferring phosphorus-containing groups (GO:0016772), nucleotide binding (GO:0000166), ribonucleotide binding (GO:0032553), protein serine/threonine kinase activity (GO:0004674), kinase activity (GO:0016301), phosphotransferase activity, alcohol group as acceptor (GO:0016773), purine nucleotide binding (GO:0017076), purine ribonucleoside triphosphate binding (GO:0035639), purine ribonucleotide binding (GO:0032555), ATP binding (GO:0005524), adenyl ribonucleotide binding (GO:0032559), AMP-activated protein kinase activity (GO:0004679), adenyl nucleotide binding (GO:0030554)

Biological Process: biological_process (GO:0008150), metabolic process (GO:0008152), positive regulation of biological process (GO:0048518), regulation of biological process (GO:0050789), homeostatic process (GO:0042592), multicellular organismal process (GO:0032501), biological regulation (GO:0065007), response to stimulus (GO:0050896), cellular process (GO:0009987), response to chemical (GO:0042221), regulation of metabolic process (GO:0019222), nitrogen compound metabolic process (GO:0006807), organic substance metabolic process (GO:0071704), response to activity (GO:0014823), multicellular organismal-level homeostasis (GO:0048871), chemical homeostasis (GO:0048878), cellular homeostasis (GO:0019725), cellular metabolic process (GO:0044237), positive regulation of cellular process (GO:0048522), response to endogenous stimulus (GO:0009719), regulation of cellular process (GO:0050794), positive regulation of metabolic process (GO:0009893), cellular response to stimulus (GO:0051716), primary metabolic process (GO:0044238), lipid homeostasis (GO:0055088), organonitrogen compound metabolic process (GO:1901564), positive regulation of carbohydrate metabolic process (GO:0045913), energy homeostasis (GO:0097009), protein metabolic process (GO:0019538), carbohydrate homeostasis (GO:0033500), cellular response to endogenous stimulus (GO:0071495), response to oxygen-containing compound (GO:1901700), macromolecule metabolic process (GO:0043170), response to organic substance (GO:0010033), phosphorus metabolic process (GO:0006793), regulation of catabolic process (GO:0009894), positive regulation of small molecule metabolic process (GO:0062013), intracellular chemical homeostasis (GO:0055082), response to inorganic substance (GO:0010035), response to nitrogen compound (GO:1901698), positive regulation of cellular metabolic process (GO:0031325), cellular response to chemical stimulus (GO:0070887), regulation of small molecule metabolic process (GO:0062012), regulation of nitrogen compound metabolic process (GO:0051171), regulation of cellular metabolic process (GO:0031323), regulation of primary metabolic process (GO:0080090), positive regulation of catabolic process (GO:0009896), response to salt (GO:1902074), positive regulation of nitrogen compound metabolic process (GO:0051173), response to metal ion (GO:0010038), cellular response to organonitrogen compound (GO:0071417), fatty acid homeostasis (GO:0055089), response to carbohydrate (GO:0009743), regulation of carbohydrate catabolic process (GO:0043470), positive regulation of phosphorus metabolic process (GO:0010562), cellular response to organic substance (GO:0071310), cellular response to salt (GO:1902075), cellular response to nitrogen compound (GO:1901699), phosphate-containing compound metabolic process (GO:0006796), regulation of carbohydrate metabolic process (GO:0006109), protein modification process (GO:0036211), regulation of nucleotide metabolic process (GO:0006140), positive regulation of nucleobase-containing compound metabolic process (GO:0045935), response to calcium ion (GO:0051592), regulation of generation of precursor metabolites and energy (GO:0043467), macromolecule modification (GO:0043412), response to organonitrogen compound (GO:0010243), cellular response to inorganic substance (GO:0071241), positive regulation of glycolytic process (GO:0045821), glucose homeostasis (GO:0042593), positive regulation of nucleotide metabolic process (GO:0045981), regulation of nucleobase-containing compound metabolic process (GO:0019219), positive regulation of cellular catabolic process (GO:0031331), response to organic cyclic compound (GO:0014070), regulation of lipid metabolic process (GO:0019216), regulation of cellular catabolic process (GO:0031329), cellular response to oxygen-containing compound (GO:1901701), intracellular glucose homeostasis (GO:0001678), regulation of phosphorus metabolic process (GO:0051174), regulation of purine nucleotide metabolic process (GO:1900542), response to alkaloid (GO:0043279), regulation of glycolytic process (GO:0006110), cellular response to calcium ion (GO:0071277), positive regulation of phosphate metabolic process (GO:0045937), cellular response to carbohydrate stimulus (GO:0071322), cellular response to glucose stimulus (GO:0071333), protein phosphorylation (GO:0006468), response to monosaccharide (GO:0034284), regulation of phosphate metabolic process (GO:0019220), phosphorylation (GO:0016310), cellular response to metal ion (GO:0071248), positive regulation of purine nucleotide metabolic process (GO:1900544), response to purine-containing compound (GO:0014074), regulation of phosphorylation (GO:0042325), regulation of ATP metabolic process (GO:1903578), cellular response to monosaccharide stimulus (GO:0071326), response to caffeine (GO:0031000), positive regulation of phosphorylation (GO:0042327), response to hexose (GO:0009746), positive regulation of ATP metabolic process (GO:1903580), cellular response to hexose stimulus (GO:0071331), response to glucose (GO:0009749)

Cellular Component: cellular_component (GO:0005575), protein-containing complex (GO:0032991), cellular anatomical entity (GO:0110165), intracellular anatomical structure (GO:0005622), organelle (GO:0043226), cell projection (GO:0042995), membrane (GO:0016020), cell body (GO:0044297), cell periphery (GO:0071944), intracellular protein-containing complex (GO:0140535), apical part of cell (GO:0045177), catalytic complex (GO:1902494), somatodendritic compartment (GO:0036477), cytoplasm (GO:0005737), membrane-enclosed lumen (GO:0031974), nucleoplasm (GO:0005654), transferase complex (GO:1990234), plasma membrane bounded cell projection (GO:0120025), intracellular organelle (GO:0043229), nucleotide-activated protein kinase complex (GO:0031588), apical plasma membrane (GO:0016324), neuronal cell body (GO:0043025), plasma membrane region (GO:0098590), organelle lumen (GO:0043233), dendritic tree (GO:0097447), membrane-bounded organelle (GO:0043227), plasma membrane (GO:0005886), intracellular membrane-bounded organelle (GO:0043231), transferase complex, transferring phosphorus-containing groups (GO:0061695), dendrite (GO:0030425), neuron projection (GO:0043005), intracellular organelle lumen (GO:0070013), nucleus (GO:0005634), protein kinase complex (GO:1902911), nuclear lumen (GO:0031981), axon (GO:0030424)

Generated by BioReason

Bioreason Rl Review

(Prkaa2-bioreason-rl-review.md)

BioReason-Pro RL Review: Prkaa2 (rat)

Source: Prkaa2-bioreason-rl-predictions.md

  • Correctness: 4/5
  • Completeness: 4/5

Functional Summary Review

The functional summary states:

A soluble energy-regulated serine/threonine kinase that uses an N-terminal catalytic core and a C-terminal adenylate-responsive module to phosphorylate metabolic and cytoskeletal substrates. Autoinhibitory elements restrain basal activity until relief by upstream phosphorylation and adenylate sensing. Operating primarily in the cytoplasm with regulated access to the nucleus, it coordinates energy-stress signaling and broader cellular economy by coupling nucleotide sensing to substrate phosphorylation.

This is largely correct and captures the core biology of AMPK alpha-2. The curated review confirms protein serine/threonine kinase activity (GO:0004674), AMP-activated protein kinase activity (GO:0004679), ATP binding (GO:0005524), energy homeostasis functions, and cytoplasm/nucleus localization. The description of the autoinhibitory domain, adenylate sensor, and heterotrimeric complex assembly is well-supported.

One issue: while the summary mentions "metabolic and cytoskeletal substrates," the curated review emphasizes metabolic substrates (ACC, HMGCR, PFK-2, ChREBP, TSC2, Raptor) far more than cytoskeletal targets. The repeated mention of "cytoskeletal" substrates in the summary and thinking trace appears to be driven by the KA1 domain annotation, which BioReason interprets as mediating cytoskeletal interactions. While AMPK does have roles in cell polarity and cytoskeletal regulation, this emphasis slightly overstates what is a secondary function relative to the primary metabolic control role. This is a minor accuracy issue.

The curated review also highlights chromatin remodeling (GO:0006338) via histone H2B phosphorylation, positive regulation of autophagy (GO:0010508), and cellular response to glucose starvation (GO:0042149) -- none of which are mentioned in the BioReason summary. These represent important biology that the domain-based reasoning does not capture.

Comparison with interpro2go:

The interpro2go annotation for Prkaa2 is protein kinase activity (GO:0004672), which the curated review marks for REMOVE as too general. BioReason's summary goes well beyond this, correctly identifying the AMPK-specific context from the autoinhibitory domain (IPR028783/IPR049020) and adenylate sensor domain (IPR032270). The specific AMPK identity is correctly inferred from domain architecture rather than just recapitulating the generic kinase annotation. This represents genuine added value.

Notes on thinking trace

The trace provides a thorough domain-by-domain analysis and correctly identifies the AMPK catalytic subunit architecture. The hypothesis about heterotrimeric complex formation with beta and gamma subunits is accurate. The overemphasis on cytoskeletal substrates appears to stem from over-interpreting the KA1 domain's function. The KA1 domain in AMPK alpha subunits primarily mediates membrane/lipid association and scaffold interactions rather than direct cytoskeletal targeting.

📄 View Raw YAML

 
id: Q09137
gene_symbol: Prkaa2
taxon:
  id: NCBITaxon:10116
  label: Rattus norvegicus
description: PRKAA2 encodes the alpha-2 catalytic subunit of AMP-activated 
  protein kinase (AMPK), a central cellular energy sensor that maintains energy 
  homeostasis. As a serine/threonine kinase, PRKAA2 is activated when cellular 
  AMP/ATP ratios rise, triggering phosphorylation of metabolic enzymes to 
  suppress anabolic processes (fatty acid/cholesterol synthesis) while promoting
  catabolic processes (fatty acid oxidation, glycolysis, autophagy). The protein
  forms heterotrimeric complexes with regulatory beta and gamma subunits, 
  localizes to both cytoplasm and nucleus, and phosphorylates key substrates 
  including ACC (fatty acid synthesis), HMGCR (cholesterol synthesis), PFK-2 
  (glycolysis), and ChREBP (transcriptional regulation). Recent discoveries 
  highlight its direct role in chromatin remodeling via histone H2B 
  phosphorylation under stress conditions.
existing_annotations:
  - term:
      id: GO:0004674
      label: protein serine/threonine kinase activity
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Core catalytic function strongly supported by extensive 
        biochemical evidence. PRKAA2 phosphorylates serine/threonine residues on
        numerous substrates (ACC, HMGCR, PFK-2, ChREBP, TSC2, Raptor). Multiple 
        IDA studies confirm this activity (PMID:8955377, PMID:12065578).
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research.md
          supporting_text: Generated using OpenAI Deep Research API
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            Prkaa2 encodes a **protein kinase** (EC 2.7.11.1; Ser/Thr kinase).
  - term:
      id: GO:0010508
      label: positive regulation of autophagy
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Well-established function through ULK1 phosphorylation and mTORC1
        inhibition. However, 2024 research shows complexity - AMPK can suppress 
        autophagy in specific contexts. Keep as important but context-dependent 
        function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0042149
      label: cellular response to glucose starvation
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Core function - AMPK is the primary cellular glucose/energy
        sensor. Activated by low glucose via AMP/ATP ratio changes. Knockout
        mice show impaired glucose homeostasis. Multiple ISS/ISO annotations
        support this.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation.
  - term:
      id: GO:0006338
      label: chromatin remodeling
    evidence_type: IEA
    original_reference_id: GO_REF:0000108
    review:
      summary: Supported by evidence that AMPK/PRKAA2 phosphorylates histone H2B
        under metabolic stress, linking energy sensing to chromatin remodeling.
      action: ACCEPT
      reason: Chromatin remodeling is supported by histone H2B Ser36
        phosphorylation in stress conditions, aligning with core_functions that
        capture this epigenetic regulation.
  - term:
      id: GO:0004672
      label: protein kinase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: Too general - more specific terms available (serine/threonine 
        kinase, AMP-activated protein kinase). Redundant with better-annotated 
        specific terms.
      action: REMOVE
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Core defining function of PRKAA2. Multiple IDA studies confirm
        (PMID:11069105, PMID:11724780, PMID:14511394). This is THE primary
        molecular function.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation.
  - term:
      id: GO:0005524
      label: ATP binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Essential for kinase function - ATP is the phosphate donor. IDA
        evidence exists (PMID:16648175). Crystal structures confirm ATP-binding
        pocket.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            The α subunit provides the **catalytic kinase activity** and is activated primarily by phosphorylation at a conserved threonine within the activation loop (**Thr172 for α2**), which is a core mechanistic definition of “AMPK activation.”
  - term:
      id: GO:0000166
      label: nucleotide binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too general - ATP binding is more specific and already annotated.
        Redundant.
      action: REMOVE
  - term:
      id: GO:0004674
      label: protein serine/threonine kinase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Automated annotation consistent with IBA and IDA evidence. Core 
        kinase function.
      action: ACCEPT
  - term:
      id: GO:0006325
      label: chromatin organization
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Weak IEA evidence. While H2B phosphorylation occurs, this is 
        stress-specific and not a primary function. Too broad.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0006629
      label: lipid metabolic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Core function via ACC and HMGCR phosphorylation. Controls fatty 
        acid and cholesterol synthesis. Strong experimental support 
        (PMID:12065578). However, more specific terms available.
      action: ACCEPT
  - term:
      id: GO:0006631
      label: fatty acid metabolic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Core function - directly regulates ACC to control fatty acid 
        synthesis/oxidation balance. IDA evidence for fatty acid homeostasis 
        (PMID:11724780).
      action: ACCEPT
  - term:
      id: GO:0006633
      label: fatty acid biosynthetic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: AMPK actually INHIBITS fatty acid synthesis by phosphorylating 
        ACC. This annotation implies positive regulation which is incorrect.
      action: REMOVE
  - term:
      id: GO:0006694
      label: steroid biosynthetic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too broad and AMPK generally inhibits steroid/cholesterol 
        synthesis. More specific negative regulation terms would be appropriate.
      action: REMOVE
  - term:
      id: GO:0006695
      label: cholesterol biosynthetic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: AMPK INHIBITS cholesterol synthesis via HMGCR phosphorylation. 
        This term implies positive regulation which is incorrect.
      action: REMOVE
  - term:
      id: GO:0006914
      label: autophagy
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too broad - 'positive regulation of autophagy' is more accurate. 
        Complex bidirectional regulation discovered in 2024.
      action: REMOVE
  - term:
      id: GO:0008202
      label: steroid metabolic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too broad. AMPK's role is more specific to cholesterol metabolism
        inhibition.
      action: REMOVE
  - term:
      id: GO:0008203
      label: cholesterol metabolic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: AMPK regulates cholesterol metabolism primarily through HMGCR 
        inhibition. Keep but note the regulatory direction.
      action: ACCEPT
      reason: PRKAA2 directly phosphorylates and inhibits HMGCR, making
        cholesterol metabolism a core regulated process in energy stress.
  - term:
      id: GO:0016055
      label: Wnt signaling pathway
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Weak evidence, likely indirect effect. May phosphorylate 
        beta-catenin but not a primary function. IEA only.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0016126
      label: sterol biosynthetic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: AMPK inhibits rather than promotes sterol synthesis. Misleading 
        annotation.
      action: REMOVE
  - term:
      id: GO:0016301
      label: kinase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too general - more specific terms (protein serine/threonine 
        kinase, AMP-activated protein kinase) are already annotated.
      action: REMOVE
  - term:
      id: GO:0016740
      label: transferase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Far too general - specific kinase terms already present. No value
        added.
      action: REMOVE
  - term:
      id: GO:0031000
      label: response to caffeine
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: IDA evidence exists (PMID:19608206) showing caffeine activates 
        AMPK in muscle. However, this is a pharmacological response, not a core 
        function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0045821
      label: positive regulation of glycolytic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Core function - AMPK phosphorylates PFK-2 at Ser466 to activate 
        glycolysis. Strong IDA evidence (PMID:11069105). Critical for ATP 
        generation under stress.
      action: ACCEPT
  - term:
      id: GO:0046872
      label: metal ion binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Mg2+ binding is required for kinase activity (coordinates ATP). 
        Standard feature of protein kinases. Could be more specific.
      action: MODIFY
      proposed_replacement_terms:
        - id: GO:0000287
          label: magnesium ion binding
  - term:
      id: GO:0047322
      label: '[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity'
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Specific substrate phosphorylation well-documented 
        (PMID:2369897). Important for cholesterol homeostasis. Keep as it 
        provides mechanistic specificity.
      action: ACCEPT
  - term:
      id: GO:0048511
      label: rhythmic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: Too vague. 'Regulation of circadian rhythm' is more specific and 
        has better evidence. Redundant.
      action: REMOVE
  - term:
      id: GO:0055089
      label: fatty acid homeostasis
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Core function with strong IDA evidence (PMID:11724780). AMPK 
        balances fatty acid synthesis/oxidation via ACC phosphorylation.
      action: ACCEPT
  - term:
      id: GO:0071277
      label: cellular response to calcium ion
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: AMPK is activated by CaMKK2 in response to calcium. IMP evidence 
        exists (PMID:25788287). Important regulatory mechanism but not primary 
        function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071333
      label: cellular response to glucose stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Core function - responds to both high and low glucose. IMP 
        evidence (PMID:25788287). Central to glucose homeostasis.
      action: ACCEPT
  - term:
      id: GO:0097009
      label: energy homeostasis
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: THE core function of AMPK - master regulator of cellular energy
        balance. Strong IDA evidence (PMID:11724780). Fundamental role.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            Functionally, AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy
  - term:
      id: GO:0106310
      label: protein serine kinase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000116
    review:
      summary: Redundant with 'protein serine/threonine kinase activity' which 
        is more complete and has better evidence.
      action: REMOVE
  - term:
      id: GO:0031669
      label: cellular response to nutrient levels
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Core function - AMPK senses and responds to nutrient 
        availability. Strong ISO evidence from mouse. Fundamental role in 
        metabolism. RETIRED - GO_REF:0000096 no longer used in GOA.
      action: ACCEPT
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Duplicate annotation - core AMPK function already reviewed as IBA
        evidence type. This ISO annotation provides additional ortholog-based 
        support for the same function. RETIRED - GO_REF:0000096 no longer used 
        in GOA.
      action: ACCEPT
  - term:
      id: GO:0004674
      label: protein serine/threonine kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog-based annotation consistent with IBA and IDA evidence. 
        Core kinase function. RETIRED - GO_REF:0000096 no longer used in GOA.
      action: ACCEPT
  - term:
      id: GO:0140823
      label: histone H2BS36 kinase activity
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Evidence for H2B Ser36 phosphorylation by AMPK under stress 
        conditions is well-established in mammals. This is a specific 
        stress-response function supported by experimental data.
      action: ACCEPT
  - term:
      id: GO:0140823
      label: histone H2BS36 kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for H2B Ser36 phosphorylation under stress 
        conditions.
      action: ACCEPT
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Strong evidence - PMID:25788287 shows calcium-dependent AMPK 
        activation in neurons. IMP evidence for core AMPK function.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: Polarized activities of AMPK and BRSK in primary 
            hippocampal neurons
  - term:
      id: GO:0042149
      label: cellular response to glucose starvation
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Sequence similarity evidence for glucose starvation response. 
        Core AMPK function.
      action: ACCEPT
  - term:
      id: GO:0042149
      label: cellular response to glucose starvation
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for glucose starvation response. Core AMPK 
        function.
      action: ACCEPT
  - term:
      id: GO:1905691
      label: lipid droplet disassembly
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: AMPK promotes lipolysis and lipid droplet breakdown via 
        phosphorylation of lipases and metabolic enzymes. This is supported by 
        evidence of AMPK activating lipid oxidation pathways.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:1905691
      label: lipid droplet disassembly
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for AMPK role in lipid droplet breakdown.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0062028
      label: regulation of stress granule assembly
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: AMPK responds to stress conditions and may influence stress 
        granule formation, but evidence is indirect. Likely over-annotation as 
        not a primary function.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0010629
      label: negative regulation of gene expression
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: AMPK negatively regulates lipogenic genes (ChREBP, SREBP) and 
        anabolic gene programs. However, term is too broad - more specific terms
        would be better.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0034599
      label: cellular response to oxidative stress
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: AMPK is activated during oxidative stress and promotes protective
        responses including autophagy. This is a legitimate stress response 
        function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0070507
      label: regulation of microtubule cytoskeleton organization
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Weak evidence - AMPK may indirectly affect cytoskeleton but this 
        is not a well-established primary function. Likely over-annotation.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0071277
      label: cellular response to calcium ion
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for calcium-dependent AMPK activation. 
        Important regulatory mechanism.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071277
      label: cellular response to calcium ion
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Strong evidence - PMID:25788287 demonstrates calcium-dependent 
        AMPK activation via CaMKK2 pathway. Important regulatory mechanism but 
        not core metabolic function.
      action: KEEP_AS_NON_CORE
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: 2015 Mar 18. Polarized activities of AMPK and BRSK in
            primary hippocampal neurons.
  - term:
      id: GO:0071333
      label: cellular response to glucose stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for glucose response. Core AMPK function.
      action: ACCEPT
  - term:
      id: GO:0071333
      label: cellular response to glucose stimulus
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Strong supporting evidence for core glucose sensing function. IMP
        evidence adds to already accepted IEA annotation.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: Polarized activities of AMPK and BRSK in primary 
            hippocampal neurons
  - term:
      id: GO:0010468
      label: regulation of gene expression
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Too broad - AMPK regulates specific gene sets via ChREBP, SREBP, 
        p53, etc. More specific terms would be preferable.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0014850
      label: response to muscle activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Well-established function - AMPK is activated during muscle 
        contraction and exercise. Important for muscle energy metabolism 
        adaptation.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071466
      label: cellular response to xenobiotic stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: AMPK can be activated by xenobiotics like AICAR, metformin, and 
        other compounds. Secondary response, not core function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0016241
      label: regulation of macroautophagy
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: More specific than general autophagy term. AMPK regulates 
        macroautophagy via ULK1 phosphorylation and mTORC1 inhibition. 
        Established function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0016241
      label: regulation of macroautophagy
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for macroautophagy regulation. Established 
        function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071380
      label: cellular response to prostaglandin E stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Very specific response that may occur but is not well-documented 
        as primary function. Likely over-annotation.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0004712
      label: protein serine/threonine/tyrosine kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: AMPK is primarily serine/threonine kinase, not tyrosine. This 
        broader term is less accurate than the specific serine/threonine kinase 
        annotation.
      action: REMOVE
  - term:
      id: GO:0003682
      label: chromatin binding
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: AMPK translocates to nucleus under stress and binds chromatin to 
        phosphorylate histones. Evidence from H2B phosphorylation studies 
        supports this.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0003682
      label: chromatin binding
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for chromatin binding during stress responses.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IDA
    original_reference_id: PMID:11069105
    review:
      summary: Strong direct evidence for core AMPK function. PMID:11069105 
        demonstrates AMPK phosphorylation of PFK-2, confirming kinase activity.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:11069105
          supporting_text: Phosphorylation and activation of heart PFK-2 by AMPK
            has a role in the stimulation of glycolysis during ischaemia
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IDA
    original_reference_id: PMID:11724780
    review:
      summary: Strong direct evidence for core AMPK function. PMID:11724780 
        demonstrates AMPK phosphorylation of ChREBP, confirming kinase activity.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:11724780
          supporting_text: 'Mechanism for fatty acid "sparing" effect on glucose-induced
            transcription: regulation of carbohydrate-responsive element-binding protein
            by AMP-activated protein kinase'
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:11069105
    review:
      summary: Too general - AMPK binds many proteins but more specific terms 
        would be better (complex binding, substrate binding). Remove as 
        uninformative.
      action: REMOVE
      supported_by:
        - reference_id: PMID:11069105
          supporting_text: Phosphorylation and activation of heart PFK-2 by AMPK
            has a role in the stimulation of glycolysis during ischaemia.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:11724780
    review:
      summary: Too general - AMPK binds many proteins but more specific terms 
        would be better. Remove as uninformative.
      action: REMOVE
      supported_by:
        - reference_id: PMID:11724780
          supporting_text: 'Nov 27. Mechanism for fatty acid "sparing" effect on glucose-induced
            transcription: regulation of carbohydrate-responsive element-binding protein
            by AMP-activated protein kinase.'
  - term:
      id: GO:0008610
      label: lipid biosynthetic process
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Misleading - AMPK actually INHIBITS lipid biosynthesis by 
        phosphorylating ACC and other enzymes. This should be negative 
        regulation.
      action: REMOVE
  - term:
      id: GO:0008610
      label: lipid biosynthetic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Misleading - AMPK actually INHIBITS lipid biosynthesis. Remove 
        incorrect annotation.
      action: REMOVE
  - term:
      id: GO:0010508
      label: positive regulation of autophagy
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Sequence similarity evidence for autophagy regulation. Complex 
        context-dependent function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0010508
      label: positive regulation of autophagy
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for autophagy regulation. Complex 
        context-dependent function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0031669
      label: cellular response to nutrient levels
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Sequence similarity evidence for nutrient sensing. Core AMPK 
        function.
      action: ACCEPT
  - term:
      id: GO:0032007
      label: negative regulation of TOR signaling
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Core function - AMPK inhibits mTORC1 via TSC2 and Raptor
        phosphorylation. Well-established mechanism for energy conservation.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
  - term:
      id: GO:0032007
      label: negative regulation of TOR signaling
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for TOR inhibition. Core metabolic regulation.
      action: ACCEPT
  - term:
      id: GO:0042752
      label: regulation of circadian rhythm
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: AMPK phosphorylates CRY1 and links metabolism to circadian 
        rhythms. However, this is not a primary metabolic function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0042752
      label: regulation of circadian rhythm
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for circadian regulation via CRY1 
        phosphorylation.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0043066
      label: negative regulation of apoptotic process
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: AMPK can promote cell survival during mild stress via autophagy 
        and p53 phosphorylation. Context-dependent protective function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0043066
      label: negative regulation of apoptotic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for cell survival promotion during stress.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0045821
      label: positive regulation of glycolytic process
    evidence_type: IDA
    original_reference_id: PMID:11069105
    review:
      summary: Strong direct evidence - PMID:11069105 demonstrates AMPK 
        phosphorylation of PFK-2 which activates glycolysis. Core metabolic 
        function.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:11069105
          supporting_text: Phosphorylation and activation of heart PFK-2 by AMPK
            has a role in the stimulation of glycolysis during ischaemia
  - term:
      id: GO:0055089
      label: fatty acid homeostasis
    evidence_type: IDA
    original_reference_id: PMID:11724780
    review:
      summary: Strong direct evidence - PMID:11724780 shows AMPK regulation of 
        fatty acid metabolism via ACC phosphorylation. Core function already 
        accepted from IEA.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:11724780
          supporting_text: 'Mechanism for fatty acid "sparing" effect on glucose-induced
            transcription: regulation of carbohydrate-responsive element-binding protein
            by AMP-activated protein kinase'
  - term:
      id: GO:0097009
      label: energy homeostasis
    evidence_type: IDA
    original_reference_id: PMID:11724780
    review:
      summary: Strong direct evidence - PMID:11724780 demonstrates AMPK role in 
        cellular energy balance. THE core function already accepted from IEA.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:11724780
          supporting_text: 'Mechanism for fatty acid "sparing" effect on glucose-induced
            transcription: regulation of carbohydrate-responsive element-binding protein
            by AMP-activated protein kinase'
  - term:
      id: GO:0042593
      label: glucose homeostasis
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Core function - AMPK is central to glucose homeostasis through 
        multiple mechanisms. Well-established role in glucose metabolism.
      action: ACCEPT
  - term:
      id: GO:0042593
      label: glucose homeostasis
    evidence_type: ISO
    original_reference_id: GO_REF:0000096
    retired: true
    review:
      summary: Ortholog evidence for glucose homeostasis. Core metabolic 
        function.
      action: ACCEPT
  - term:
      id: GO:0014823
      label: response to activity
    evidence_type: IDA
    original_reference_id: PMID:17253964
    review:
      summary: PMID:17253964 shows adrenergic activation of AMPK in adipocytes 
        during activity. Important physiological response but not core function.
      action: KEEP_AS_NON_CORE
      supported_by:
        - reference_id: PMID:17253964
          supporting_text: Adrenaline is a critical mediator of acute 
            exercise-induced AMP-activated protein kinase activation in 
            adipocytes.
  - term:
      id: GO:0031000
      label: response to caffeine
    evidence_type: IDA
    original_reference_id: PMID:19608206
    review:
      summary: Strong direct evidence - PMID:19608206 shows caffeine activates 
        AMPK in skeletal muscle. Pharmacological response already accepted from 
        IEA.
      action: KEEP_AS_NON_CORE
      supported_by:
        - reference_id: PMID:19608206
          supporting_text: 2009 Jul 15. Caffeine acutely activates 5'adenosine 
            monophosphate-activated protein kinase and increases 
            insulin-independent glucose transport in rat skeletal muscles.
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IDA
    original_reference_id: PMID:14511394
    review:
      summary: Strong direct evidence - PMID:14511394 demonstrates AMPK 
        complexes and upstream kinase LKB1. Direct confirmation of kinase 
        activity.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:14511394
          supporting_text: Complexes between the LKB1 tumor suppressor, STRAD 
            alpha/beta and MO25 alpha/beta are upstream kinases in the 
            AMP-activated protein kinase cascade
  - term:
      id: GO:0044877
      label: protein-containing complex binding
    evidence_type: IDA
    original_reference_id: PMID:14511394
    review:
      summary: PMID:14511394 shows AMPK interaction with LKB1-STRD-MO25 complex.
        Specific complex binding is more informative than general protein 
        binding.
      action: KEEP_AS_NON_CORE
      supported_by:
        - reference_id: PMID:14511394
          supporting_text: Complexes between the LKB1 tumor suppressor, STRAD 
            alpha/beta and MO25 alpha/beta are upstream kinases in the 
            AMP-activated protein kinase cascade.
  - term:
      id: GO:0004674
      label: protein serine/threonine kinase activity
    evidence_type: IDA
    original_reference_id: PMID:8955377
    review:
      summary: Strong direct evidence - PMID:8955377 demonstrates substrate 
        specificity differences between α1 and α2 isoforms. Core kinase 
        function.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:8955377
          supporting_text: The alpha1 and alpha2 isoforms of the AMP-activated 
            protein kinase have similar activities in rat liver but exhibit 
            differences in substrate specificity in vitro.
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IMP
    original_reference_id: PMID:10698692
    review:
      summary: IMP evidence from γ subunit characterization study. Shows 
        requirement for γ subunit in AMP binding and AMPK activation.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:10698692
          supporting_text: Characterization of AMP-activated protein kinase 
            gamma-subunit isoforms and their role in AMP binding
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IMP
    original_reference_id: PMID:8955377
    review:
      summary: IMP evidence showing differential properties of α2 vs α1 
        complexes. Demonstrates AMP-activation specifically.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:8955377
          supporting_text: The alpha1 and alpha2 isoforms of the AMP-activated 
            protein kinase have similar activities in rat liver but exhibit 
            differences in substrate specificity in vitro.
  - term:
      id: GO:0030674
      label: protein-macromolecule adaptor activity
    evidence_type: IDA
    original_reference_id: PMID:15695819
    review:
      summary: PMID:15695819 shows β subunit tethering α and γ subunits. 
        However, this refers to β subunit function, not α2 directly.
      action: REMOVE
      supported_by:
        - reference_id: PMID:15695819
          supporting_text: 2005 Jan 28. AMP-activated protein kinase beta 
            subunit tethers alpha and gamma subunits via its C-terminal sequence
            (186-270).
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: IDA
    original_reference_id: PMID:16648175
    review:
      summary: Strong direct evidence - PMID:16648175 shows AMPK activation in 
        ischemic heart. Direct biochemical demonstration of kinase activity.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:16648175
          supporting_text: Activation of AMPK alpha- and gamma-isoform complexes
            in the intact ischemic rat heart
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:16648175
    review:
      summary: Too general - while AMPK binds proteins, more specific terms are 
        preferable. Remove as uninformative.
      action: REMOVE
      supported_by:
        - reference_id: PMID:16648175
          supporting_text: Activation of AMPK alpha- and gamma-isoform complexes
            in the intact ischemic rat heart.
  - term:
      id: GO:0005524
      label: ATP binding
    evidence_type: IDA
    original_reference_id: PMID:16648175
    review:
      summary: Strong evidence - PMID:16648175 demonstrates ATP requirement for 
        AMPK activity. Core function already accepted from IEA.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:16648175
          supporting_text: Activation of AMPK alpha- and gamma-isoform complexes
            in the intact ischemic rat heart
  - term:
      id: GO:0004672
      label: protein kinase activity
    evidence_type: IDA
    original_reference_id: PMID:12065578
    review:
      summary: Too general - more specific serine/threonine and AMP-activated 
        kinase terms already accepted. Remove redundant broad term.
      action: REMOVE
      supported_by:
        - reference_id: PMID:12065578
          supporting_text: 2002 Jun 13. Coordinate regulation of malonyl-CoA 
            decarboxylase, sn-glycerol-3-phosphate acyltransferase, and 
            acetyl-CoA carboxylase by AMP-activated protein kinase in rat 
            tissues in response to exercise.
  - term:
      id: GO:0019216
      label: regulation of lipid metabolic process
    evidence_type: IDA
    original_reference_id: PMID:12065578
    review:
      summary: Strong evidence - PMID:12065578 shows AMPK regulation of ACC and 
        other lipid metabolic enzymes. Well-established function.
      action: ACCEPT
      supported_by:
        - reference_id: PMID:12065578
          supporting_text: Coordinate regulation of malonyl-CoA decarboxylase, 
            sn-glycerol-3-phosphate acyltransferase, and acetyl-CoA carboxylase 
            by AMP-activated protein kinase in rat tissues in response to 
            exercise
  - term:
      id: GO:0005634
      label: nucleus
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: AMPK localizes to both cytoplasm and nucleus depending on 
        cellular conditions. Nuclear localization is particularly important for 
        its histone H2B phosphorylation function and direct transcriptional 
        regulation under stress conditions. The α2 subunit can translocate to 
        nucleus where it phosphorylates chromatin targets and interacts with 
        transcriptional machinery.
      action: ACCEPT
      reason: Nuclear localization is essential for AMPK's stress-responsive 
        chromatin modifying activities and direct transcriptional regulation, 
        representing a key aspect of its energy-sensing function beyond 
        cytoplasmic metabolism.
  - term:
      id: GO:0005737
      label: cytoplasm
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: The cytoplasm is the primary location for AMPK's core metabolic 
        regulatory functions. Here AMPK phosphorylates key metabolic enzymes 
        including ACC (fatty acid synthesis), PFK-2 (glycolysis), HMGCR 
        (cholesterol synthesis), and TSC2/Raptor (mTORC1 signaling). The 
        majority of AMPK's energy-sensing and metabolic control activities occur
        in this compartment.
      action: ACCEPT
      reason: Cytoplasmic localization is fundamental to AMPK's primary role as 
        a metabolic energy sensor. Most of its well-characterized substrate 
        phosphorylation events occur in the cytoplasm where metabolic enzymes 
        and signaling complexes are located.
  - term:
      id: GO:1904262
      label: negative regulation of TORC1 signaling
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: AMPK directly inhibits mTORC1 by phosphorylating TSC2 and Raptor,
        a well-established energy-conservation mechanism. This TORC1-specific
        term is more precise than the generic negative regulation of TOR
        signaling annotation and reflects a core downstream signaling role.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
  - term:
      id: GO:1990044
      label: protein localization to lipid droplet
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0031588
      label: nucleotide-activated protein kinase complex
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005634
      label: nucleus
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Automated annotation consistent with experimental evidence. 
        Nuclear localization supports stress-responsive functions including 
        histone phosphorylation and transcriptional regulation.
      action: ACCEPT
      reason: Supports the manually curated IBA annotation with additional 
        automated evidence for nuclear localization.
  - term:
      id: GO:0005737
      label: cytoplasm
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: Automated annotation consistent with experimental evidence. 
        Cytoplasmic localization is where AMPK performs most of its metabolic 
        regulatory functions through substrate phosphorylation.
      action: ACCEPT
      reason: Supports the manually curated IBA annotation with additional 
        automated evidence for cytoplasmic localization.
  - term:
      id: GO:0030424
      label: axon
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0030425
      label: dendrite
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0031588
      label: nucleotide-activated protein kinase complex
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0043025
      label: neuronal cell body
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005634
      label: nucleus
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Ortholog-based annotation from mouse-rat comparisons. Nuclear 
        localization is conserved across mammalian AMPK α2 subunits for 
        stress-responsive chromatin functions.
      action: ACCEPT
      reason: Strong orthology evidence supports nuclear localization, 
        consistent with other annotation types.
  - term:
      id: GO:0031588
      label: nucleotide-activated protein kinase complex
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0031669
      label: cellular response to nutrient levels
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005654
      label: nucleoplasm
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005794
      label: Golgi apparatus
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0016607
      label: nuclear speck
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0036064
      label: ciliary basal body
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:1904262
      label: negative regulation of TORC1 signaling
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Sequence-similarity support for AMPK-mediated inhibition of mTORC1
        via TSC2/Raptor phosphorylation. Consistent with the curated IBA
        annotation for this TORC1-specific term.
      action: ACCEPT
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
  - term:
      id: GO:1904262
      label: negative regulation of TORC1 signaling
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Ortholog-based support for AMPK-mediated inhibition of mTORC1.
        Consistent with the curated IBA/ISS annotations for this TORC1-specific
        term.
      action: ACCEPT
  - term:
      id: GO:0002181
      label: cytoplasmic translation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0009267
      label: cellular response to starvation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0034198
      label: cellular response to amino acid starvation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0038202
      label: TORC1 signaling
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0042149
      label: cellular response to glucose starvation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0045947
      label: negative regulation of translational initiation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0045948
      label: positive regulation of translational initiation
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0061462
      label: protein localization to lysosome
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0085020
      label: protein K6-linked ubiquitination
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:1904263
      label: positive regulation of TORC1 signaling
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Direction contradicts AMPK's canonical and well-established role -
        AMPKα2 is a negative regulator of mTORC1 (via TSC2/Raptor
        phosphorylation), not a positive regulator. This ortholog-transferred
        annotation attributes the opposite regulatory direction and is
        factually incorrect, not merely imprecise, so it should be removed.
      action: REMOVE
      supported_by:
        - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
          supporting_text: |-
            AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
  - term:
      id: GO:0004674
      label: protein serine/threonine kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0140823
      label: histone H2BS36 kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:1905691
      label: lipid droplet disassembly
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:1990044
      label: protein localization to lipid droplet
    evidence_type: ISS
    original_reference_id: GO_REF:0000024
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:1990044
      label: protein localization to lipid droplet
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0006646
      label: phosphatidylethanolamine biosynthetic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0006656
      label: phosphatidylcholine biosynthetic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0090200
      label: positive regulation of release of cytochrome c from mitochondria
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0097284
      label: hepatocyte apoptotic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:1903944
      label: negative regulation of hepatocyte apoptotic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005737
      label: cytoplasm
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Ortholog-based annotation from mouse-rat comparisons. Cytoplasmic
        localization is conserved across mammalian AMPK α2 subunits for 
        metabolic regulatory functions.
      action: ACCEPT
      reason: Strong orthology evidence supports cytoplasmic localization, 
        consistent with other annotation types and functional requirements.
  - term:
      id: GO:0062028
      label: regulation of stress granule assembly
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Likely over-annotation; term is too broad for PRKAA2.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0010494
      label: cytoplasmic stress granule
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0010629
      label: negative regulation of gene expression
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0030424
      label: axon
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0030424
      label: axon
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: 2015 Mar 18. Polarized activities of AMPK and BRSK in
            primary hippocampal neurons.
  - term:
      id: GO:0030425
      label: dendrite
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0030425
      label: dendrite
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: 2015 Mar 18. Polarized activities of AMPK and BRSK in
            primary hippocampal neurons.
  - term:
      id: GO:0034599
      label: cellular response to oxidative stress
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0043025
      label: neuronal cell body
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0043025
      label: neuronal cell body
    evidence_type: IMP
    original_reference_id: PMID:25788287
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:25788287
          supporting_text: 2015 Mar 18. Polarized activities of AMPK and BRSK in
            primary hippocampal neurons.
  - term:
      id: GO:0070507
      label: regulation of microtubule cytoskeleton organization
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Likely over-annotation; term is too broad for PRKAA2.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0071277
      label: cellular response to calcium ion
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071333
      label: cellular response to glucose stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:1903829
      label: positive regulation of protein localization
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0010468
      label: regulation of gene expression
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0014850
      label: response to muscle activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071466
      label: cellular response to xenobiotic stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0016241
      label: regulation of macroautophagy
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0071380
      label: cellular response to prostaglandin E stimulus
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Likely over-annotation; term is too broad for PRKAA2.
      action: MARK_AS_OVER_ANNOTATED
  - term:
      id: GO:0004712
      label: protein serine/threonine/tyrosine kinase activity
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Annotation is overly general or unsupported in this context and should be removed.
      action: REMOVE
  - term:
      id: GO:0003682
      label: chromatin binding
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0008610
      label: lipid biosynthetic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Annotation is overly general or unsupported in this context and should be removed.
      action: REMOVE
  - term:
      id: GO:0010508
      label: positive regulation of autophagy
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0032007
      label: negative regulation of TOR signaling
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0042752
      label: regulation of circadian rhythm
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0043066
      label: negative regulation of apoptotic process
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: Evidence supports the term but it is not core to PRKAA2 function.
      action: KEEP_AS_NON_CORE
  - term:
      id: GO:0042593
      label: glucose homeostasis
    evidence_type: ISO
    original_reference_id: GO_REF:0000121
    review:
      summary: ISO annotation consistent with curated evidence for this term.
      action: ACCEPT
  - term:
      id: GO:0005737
      label: cytoplasm
    evidence_type: IDA
    original_reference_id: PMID:18256313
    review:
      summary: Direct experimental evidence from PMID:18256313 showing AMPK 
        localization in renal epithelial cells. Cytoplasmic localization is 
        essential for AMPK's role in controlling glycogen synthase and other 
        metabolic targets in response to energy stress.
      action: ACCEPT
      reason: Strong experimental evidence for cytoplasmic localization where 
        AMPK performs its primary metabolic regulatory functions.
      supported_by:
        - reference_id: PMID:18256313
          supporting_text: Control of glycogen synthase through ADIPOR1-AMPK 
            pathway in renal distal tubules of normal and diabetic rats.
  - term:
      id: GO:0016324
      label: apical plasma membrane
    evidence_type: IDA
    original_reference_id: PMID:18256313
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:18256313
          supporting_text: Control of glycogen synthase through ADIPOR1-AMPK 
            pathway in renal distal tubules of normal and diabetic rats.
  - term:
      id: GO:0032991
      label: protein-containing complex
    evidence_type: IDA
    original_reference_id: PMID:14511394
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:14511394
          supporting_text: Complexes between the LKB1 tumor suppressor, STRAD 
            alpha/beta and MO25 alpha/beta are upstream kinases in the 
            AMP-activated protein kinase cascade.
  - term:
      id: GO:0031588
      label: nucleotide-activated protein kinase complex
    evidence_type: IDA
    original_reference_id: PMID:16648175
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
      supported_by:
        - reference_id: PMID:16648175
          supporting_text: Activation of AMPK alpha- and gamma-isoform complexes
            in the intact ischemic rat heart.
  - term:
      id: GO:0005654
      label: nucleoplasm
    evidence_type: TAS
    original_reference_id: Reactome:R-RNO-164087
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
  - term:
      id: GO:0005654
      label: nucleoplasm
    evidence_type: TAS
    original_reference_id: Reactome:R-RNO-164106
    review:
      summary: Not reviewed in this pass; requires literature review.
      action: UNDECIDED
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with
      GO terms.
  - id: GO_REF:0000024
    title: Manual transfer of experimentally-verified manual GO annotation data 
      to orthologs by curator judgment of sequence similarity.
  - id: GO_REF:0000033
    title: Annotation inferences using phylogenetic trees
  - id: GO_REF:0000043
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword 
      mapping
  - id: GO_REF:0000096
    title: Automated transfer of experimentally-verified manual GO annotation 
      data to mouse-rat orthologs.
  - id: GO_REF:0000108
    title: Automatic assignment of GO terms using logical inference, based on on
      inter-ontology links.
  - id: GO_REF:0000116
    title: Automatic Gene Ontology annotation based on Rhea mapping.
  - id: GO_REF:0000117
    title: Electronic Gene Ontology annotations created by ARBA machine learning
      models
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods.
  - id: PMID:10698692
    title: Characterization of AMP-activated protein kinase gamma-subunit 
      isoforms and their role in AMP binding.
  - id: PMID:11069105
    title: Phosphorylation and activation of heart PFK-2 by AMPK has a role in 
      the stimulation of glycolysis during ischaemia.
  - id: PMID:11724780
    title: 'Mechanism for fatty acid "sparing" effect on glucose-induced transcription:
      regulation of carbohydrate-responsive element-binding protein by AMP-activated
      protein kinase.'
  - id: PMID:12065578
    title: Coordinate regulation of malonyl-CoA decarboxylase, 
      sn-glycerol-3-phosphate acyltransferase, and acetyl-CoA carboxylase by 
      AMP-activated protein kinase in rat tissues in response to exercise.
  - id: PMID:14511394
    title: Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and 
      MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase 
      cascade.
  - id: PMID:15695819
    title: AMP-activated protein kinase beta subunit tethers alpha and gamma 
      subunits via its C-terminal sequence (186-270).
  - id: PMID:16648175
    title: Activation of AMPK alpha- and gamma-isoform complexes in the intact 
      ischemic rat heart.
  - id: PMID:17253964
    title: Adrenaline is a critical mediator of acute exercise-induced 
      AMP-activated protein kinase activation in adipocytes.
  - id: PMID:19608206
    title: Caffeine acutely activates 5'adenosine monophosphate-activated 
      protein kinase and increases insulin-independent glucose transport in rat 
      skeletal muscles.
  - id: PMID:25788287
    title: Polarized activities of AMPK and BRSK in primary hippocampal neurons.
  - id: PMID:8955377
    title: The alpha1 and alpha2 isoforms of the AMP-activated protein kinase 
      have similar activities in rat liver but exhibit differences in substrate 
      specificity in vitro.
  - id: PMID:2369897
    title: 'Regulation of HMG-CoA reductase: identification of the site phosphorylated
      by the AMP-activated protein kinase in vitro and in intact rat liver.'
  - id: file:rat/Prkaa2/Prkaa2-deep-research.md
    title: Deep research synthesis for PRKAA2 functions and regulation
  - id: file:rat/Prkaa2/Prkaa2-notes.md
    title: Research notes on PRKAA2 with literature citations
  - id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
    title: Falcon (Edison Scientific) deep research report for rat Prkaa2 (AMPKα2)
    findings:
      - statement: |-
          Prkaa2 encodes the catalytic alpha-2 subunit of the heterotrimeric
          AMPK serine/threonine kinase; the alpha subunit carries the catalytic
          kinase activity.
        supporting_text: |-
          AMPK is a **heterotrimeric serine/threonine kinase** consisting of a **catalytic α** subunit plus **regulatory β and γ** subunits.
        reference_section_type: OTHER
      - statement: |-
          The alpha subunit provides the catalytic kinase activity and is
          activated by phosphorylation at Thr172 in the activation loop.
        supporting_text: |-
          The α subunit provides the **catalytic kinase activity** and is activated primarily by phosphorylation at a conserved threonine within the activation loop (**Thr172 for α2**), which is a core mechanistic definition of “AMPK activation.”
        reference_section_type: OTHER
      - statement: |-
          Prkaa2 is a protein serine/threonine kinase (EC 2.7.11.1).
        supporting_text: |-
          Prkaa2 encodes a **protein kinase** (EC 2.7.11.1; Ser/Thr kinase).
        reference_section_type: OTHER
      - statement: |-
          AMP binding (via the gamma subunit) allosterically activates AMPK and
          protects it from dephosphorylation, coupling ATP depletion to kinase
          activation — the basis of AMP-activated protein kinase activity.
        supporting_text: |-
          AMP binding to AMPK (via γ subunit CBS motifs) promotes AMPK activation through allosteric effects and protection from dephosphorylation, coupling ATP depletion to kinase activation.
        reference_section_type: OTHER
      - statement: |-
          Upstream kinases phosphorylate AMPKα2 at Thr172, with LKB1 as a primary
          kinase and CaMKKβ/CAMKK2 as a calcium-responsive route.
        supporting_text: |-
          upstream kinases phosphorylate AMPKα2 at **Thr172**, with **LKB1** frequently highlighted as a primary kinase
        reference_section_type: OTHER
      - statement: |-
          AMPKα2 integrates energy stress to inhibit anabolic metabolism and
          promote catabolism and autophagy — its core energy-homeostasis role.
        supporting_text: |-
          Functionally, AMPKα2 integrates energy stress to inhibit anabolic metabolism and promote catabolism and autophagy
        reference_section_type: OTHER
      - statement: |-
          AMPK phosphorylates metabolic targets including ACC, HMGCR, and
          autophagy regulators such as ULK1.
        supporting_text: |-
          AMPKα2 phosphorylates metabolic targets including ACC/ACAC (canonical readout; ACC Ser79 commonly used), HMGCR, and autophagy regulators such as ULK1
        reference_section_type: OTHER
      - statement: |-
          AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor.
        supporting_text: |-
          AMPK inhibits mTORC1 via phosphorylation of TSC2 and Raptor
        reference_section_type: OTHER
      - statement: |-
          AMPKα2 has a nuclear localization signal and can shuttle to the nucleus,
          whereas α1 is primarily cytosolic.
        supporting_text: |-
          AMPKα2 contains a nuclear localization signal and can shuttle to the nucleus
        reference_section_type: OTHER
      - statement: |-
          A 2024 primary study identifies an AMPKα2-specific role in skeletal
          muscle ketone utilization via binding and stabilization of SCOT.
        supporting_text: |-
          These results place AMPKα2 as an important regulator of **skeletal muscle ketone utilization**
        reference_section_type: OTHER
  - id: GO_REF:0000121
    title: RGD ISO annotations to rat from other mammalian species.
    findings: []
  - id: PMID:18256313
    title: Control of glycogen synthase through ADIPOR1-AMPK pathway in renal 
      distal tubules of normal and diabetic rats.
    findings: []
  - id: Reactome:R-RNO-164087
    title: Phosphorylation of rChREBP(Ser 568) by rAMPK
    findings: []
  - id: Reactome:R-RNO-164106
    title: rLkb-1 (Stk-11) activates AMPK by phosphorylation
    findings: []
core_functions:
  - molecular_function:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    directly_involved_in:
      - id: GO:0097009
        label: energy homeostasis
      - id: GO:0055089
        label: fatty acid homeostasis
      - id: GO:0045821
        label: positive regulation of glycolytic process
      - id: GO:0042149
        label: cellular response to glucose starvation
      - id: GO:0032007
        label: negative regulation of TOR signaling
    locations:
      - id: GO:0005737
        label: cytoplasm
      - id: GO:0005634
        label: nucleus
    description: PRKAA2 executes ATP-dependent phosphorylation of key metabolic 
      regulatory proteins in response to cellular AMP/ATP ratio changes. Primary
      phosphorylation targets include ACC (inhibiting fatty acid synthesis), 
      PFK-2 (activating glycolysis), ChREBP (blocking lipogenic transcription), 
      HMGCR (inhibiting cholesterol synthesis), and TSC2/Raptor (suppressing 
      mTORC1). The kinase functions as part of a heterotrimeric complex 
      activated by Thr172 phosphorylation when AMP levels rise, creating a 
      molecular switch for cellular energy status.
    supported_by:
      - reference_id: PMID:10698692
      - reference_id: PMID:11069105
      - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
  - molecular_function:
      id: GO:0047322
      label: '[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity'
    directly_involved_in:
      - id: GO:0008203
        label: cholesterol metabolic process
    description: Specifically phosphorylates HMG-CoA reductase at Ser872,
      inactivating the rate-limiting enzyme of cholesterol biosynthesis to
      conserve cellular energy and NADPH during metabolic stress.
    supported_by:
      - reference_id: PMID:2369897
      - reference_id: file:rat/Prkaa2/Prkaa2-deep-research-falcon.md
  - molecular_function:
      id: GO:0140823
      label: histone H2BS36 kinase activity
    directly_involved_in:
      - id: GO:0006338
        label: chromatin remodeling
    locations:
      - id: GO:0005634
        label: nucleus
    description: Under severe metabolic stress, phosphorylates histone H2B at
      Ser36 to directly modify chromatin and activate stress-response gene
      transcription, representing a direct epigenetic mechanism linking energy
      status to gene expression.
    supported_by:
      - reference_id: GO_REF:0000024
suggested_questions:
  - question: How do the α1 and α2 subunits of AMPK differ in their tissue 
      distribution, regulation, and substrate specificity?
  - question: What determines the subcellular localization of PRKAA2-containing 
      AMPK complexes and how does this affect their function?
  - question: How does PRKAA2 contribute to metabolic sensing and energy 
      homeostasis in different physiological conditions?
  - question: What role does PRKAA2 play in cellular stress responses beyond its
      canonical metabolic functions?
  - question: Does AMPKα2's binding and stabilization of SCOT
      (succinyl-CoA:3-ketoacid CoA transferase) in skeletal muscle ketone
      utilization represent a broader non-catalytic scaffolding function, and
      can this stabilization mechanism be confirmed in rat tissues?
suggested_experiments:
  - description: Proteomics analysis to identify PRKAA2-specific substrates and 
      interacting partners compared to PRKAA1
  - description: Live-cell imaging using FRET-based biosensors to monitor 
      PRKAA2-containing AMPK activity in real-time
  - description: Metabolomics analysis of tissues from PRKAA2 knockout mice to 
      understand metabolic pathway alterations
  - description: Single-cell analysis of AMPK activity and metabolic state in
      different cell types using genetically encoded indicators
  - description: Co-immunoprecipitation and cycloheximide-chase protein stability
      assays in rat skeletal muscle to test whether AMPKα2 binds and stabilizes
      SCOT (succinyl-CoA:3-ketoacid CoA transferase) and limits its
      ubiquitin/proteasome-mediated degradation, probing a non-catalytic
      scaffolding role in ketone utilization
status: IN_PROGRESS

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