Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0030150 protein import into mitochondrial matrix	IBA GO_REF:0000033	ACCEPT	Summary: Correct and core. TIMM50 is the TIM23 presequence receptor/gatekeeper needed for import of transit peptide-containing precursors through the inner membrane toward the matrix or IMM sorting pathway. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 primarily acts on presequence-containing precursor proteins, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005744 TIM23 mitochondrial import inner membrane translocase complex	IBA GO_REF:0000033	ACCEPT	Summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence handoff and channel gating. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported. PMID:15044455 complex with human Tim23. Down-regulation of human Tim50 expression by RNA
GO:0004722 protein serine/threonine phosphatase activity	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23 presequence receptor/gatekeeper. Reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no established physiological substrate in the import pathway. Supporting Evidence: PMID:15044455 demonstrate that human Tim50 possesses phosphatase activity and is present in a file:human/TIMM50/TIMM50-deep-research-falcon.md Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates.
GO:0005743 mitochondrial inner membrane	IEA GO_REF:0000044	ACCEPT	Summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its receptor/gating domain exposed to the intermembrane space. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0016607 nuclear speck	IEA Q3ZCQ8-2 GO_REF:0000044	KEEP AS NON CORE	Summary: Supported for the Tim50a isoform, but not the core function of the canonical mitochondrial TIMM50 protein. Reason: Track as isoform-specific, non-core nuclear localization; canonical TIMM50 function is mitochondrial TIM23 import. Supporting Evidence: PMID:16008839 cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
GO:0005515 protein binding	IPI PMID:12620389 Novel raf kinase protein-protein interactions found by an ex...	MARK AS OVER ANNOTATED	Summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership. Reason: Replace generic interaction capture with TIM23 complex membership and presequence/targeting-sequence binding where supported. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005515 protein binding	IPI PMID:25852190 Integrative analysis of kinase networks in TRAIL-induced apo...	MARK AS OVER ANNOTATED	Summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership. Reason: Replace generic interaction capture with TIM23 complex membership and presequence/targeting-sequence binding where supported. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005515 protein binding	IPI PMID:31980649 Extensive rewiring of the EGFR network in colorectal cancer ...	MARK AS OVER ANNOTATED	Summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership. Reason: Replace generic interaction capture with TIM23 complex membership and presequence/targeting-sequence binding where supported. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005515 protein binding	IPI PMID:37045861 Interactome dynamics of RAF1-BRAF kinase monomers and dimers...	MARK AS OVER ANNOTATED	Summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership. Reason: Replace generic interaction capture with TIM23 complex membership and presequence/targeting-sequence binding where supported. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005743 mitochondrial inner membrane	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	ACCEPT	Summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its receptor/gating domain exposed to the intermembrane space. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0005743 mitochondrial inner membrane	NAS PMID:10339406 Genetic and structural characterization of the human mitocho...	ACCEPT	Summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its receptor/gating domain exposed to the intermembrane space. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0005744 TIM23 mitochondrial import inner membrane translocase complex	NAS PMID:10339406 Genetic and structural characterization of the human mitocho...	ACCEPT	Summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence handoff and channel gating. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported. PMID:15044455 complex with human Tim23. Down-regulation of human Tim50 expression by RNA
GO:0006886 intracellular protein transport	NAS PMID:10339406 Genetic and structural characterization of the human mitocho...	MARK AS OVER ANNOTATED	Summary: Correct pathway family but too broad. TIMM50 specifically mediates TIM23-dependent mitochondrial presequence protein import rather than general intracellular protein transport. Reason: Use mitochondrial matrix import/TIM23 terms instead of generic intracellular transport. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 primarily acts on presequence-containing precursor proteins, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion. file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0005654 nucleoplasm	IDA GO_REF:0000052	MARK AS OVER ANNOTATED	Summary: Broad nuclear localization is less informative than the isoform-specific nuclear speck evidence for Tim50a and is not the canonical TIMM50 localization. Reason: Use isoform-specific nuclear speck annotation for Tim50a; canonical TIMM50 is an inner mitochondrial membrane TIM23 subunit. Supporting Evidence: PMID:16008839 cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0005739 mitochondrion	IDA GO_REF:0000052	MARK AS OVER ANNOTATED	Summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex subunit. Reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0030150 protein import into mitochondrial matrix	IDA PMID:38828998 Reduced Protein Import via TIM23 SORT Drives Disease Patholo...	ACCEPT	Summary: Correct and core. TIMM50 is the TIM23 presequence receptor/gatekeeper needed for import of transit peptide-containing precursors through the inner membrane toward the matrix or IMM sorting pathway. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 primarily acts on presequence-containing precursor proteins, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0005739 mitochondrion	HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an...	MARK AS OVER ANNOTATED	Summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex subunit. Reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0005744 TIM23 mitochondrial import inner membrane translocase complex	IDA PMID:30598479 ROMO1 is a constituent of the human presequence translocase ...	ACCEPT	Summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence handoff and channel gating. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported. PMID:15044455 complex with human Tim23. Down-regulation of human Tim50 expression by RNA
GO:0005739 mitochondrion	IDA PMID:32848200 Ttm50 facilitates calpain activation by anchoring it to calc...	MARK AS OVER ANNOTATED	Summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex subunit. Reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions.
GO:0005783 endoplasmic reticulum	IDA PMID:32848200 Ttm50 facilitates calpain activation by anchoring it to calc...	MARK AS OVER ANNOTATED	Summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function. Reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human TIMM50-specific support. Supporting Evidence: PMID:32848200 GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that PMID:32848200 stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain PMID:32848200 magnitude. Our findings reveal the regulation of calpain activation by Ttm50, file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0005794 Golgi apparatus	IDA PMID:32848200 Ttm50 facilitates calpain activation by anchoring it to calc...	MARK AS OVER ANNOTATED	Summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function. Reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human TIMM50-specific support. Supporting Evidence: PMID:32848200 GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that PMID:32848200 stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain PMID:32848200 magnitude. Our findings reveal the regulation of calpain activation by Ttm50, file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0140608 cysteine-type endopeptidase activator activity	IDA PMID:32848200 Ttm50 facilitates calpain activation by anchoring it to calc...	MARK AS OVER ANNOTATED	Summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function. Reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human TIMM50-specific support. Supporting Evidence: PMID:32848200 GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that PMID:32848200 stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain PMID:32848200 magnitude. Our findings reveal the regulation of calpain activation by Ttm50, file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0001836 release of cytochrome c from mitochondria	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	KEEP AS NON CORE	Summary: Supported as a downstream consequence of TIMM50 depletion and mitochondrial membrane dysfunction, but it is not the core molecular/cellular role of TIMM50. Reason: TIMM50 loss can accelerate cytochrome c release, but TIMM50 itself is primarily a TIM23 import receptor/gatekeeper. Supporting Evidence: PMID:15044455 accelerating the release of cytochrome c from the mitochondria. Furthermore, file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0004721 phosphoprotein phosphatase activity	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	KEEP AS NON CORE	Summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23 presequence receptor/gatekeeper. Reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no established physiological substrate in the import pathway. Supporting Evidence: PMID:15044455 demonstrate that human Tim50 possesses phosphatase activity and is present in a file:human/TIMM50/TIMM50-deep-research-falcon.md Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates.
GO:0005134 interleukin-2 receptor binding	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	REMOVE	Summary: The cited Tim50 paper and Falcon synthesis do not support an interleukin-2 receptor binding activity for TIMM50; the established molecular role is TIM23 presequence receptor/gating. Reason: PMID:15044455 describes human Tim50 as a mitochondrial translocator/TIM23-associated protein and contains no mention of IL-2 receptor binding. This annotation appears to be a database misattribution, because a mitochondrial inner-membrane translocase subunit is not expected to function as an IL-2 receptor ligand or receptor-binding protein. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates. file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0005744 TIM23 mitochondrial import inner membrane translocase complex	IPI PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	ACCEPT	Summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence handoff and channel gating. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported. PMID:15044455 complex with human Tim23. Down-regulation of human Tim50 expression by RNA
GO:0004722 protein serine/threonine phosphatase activity	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	KEEP AS NON CORE	Summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23 presequence receptor/gatekeeper. Reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no established physiological substrate in the import pathway. Supporting Evidence: PMID:15044455 demonstrate that human Tim50 possesses phosphatase activity and is present in a file:human/TIMM50/TIMM50-deep-research-falcon.md Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates.
GO:0004725 protein tyrosine phosphatase activity	IDA PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	KEEP AS NON CORE	Summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23 presequence receptor/gatekeeper. Reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no established physiological substrate in the import pathway. Supporting Evidence: PMID:15044455 demonstrate that human Tim50 possesses phosphatase activity and is present in a file:human/TIMM50/TIMM50-deep-research-falcon.md Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates.
GO:0005515 protein binding	IPI PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	MARK AS OVER ANNOTATED	Summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership. Reason: Replace generic interaction capture with TIM23 complex membership and presequence/targeting-sequence binding where supported. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
GO:0007006 mitochondrial membrane organization	IMP PMID:15044455 Tim50, a component of the mitochondrial translocator, regula...	KEEP AS NON CORE	Summary: Supported as a cellular consequence of TIMM50 loss causing mitochondrial membrane permeabilization/dysfunction, but it is downstream of the core TIM23 import role. Reason: Keep as non-core because membrane organization phenotypes arise from impaired mitochondrial import/integrity rather than a direct membrane-organizing function. Supporting Evidence: PMID:15044455 indicate that loss of Tim50 in vertebrates causes mitochondrial membrane file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
GO:0016607 nuclear speck	IDA Q3ZCQ8-2 PMID:16008839 Tim50a, a nuclear isoform of the mitochondrial Tim50, intera...	KEEP AS NON CORE	Summary: Supported for the Tim50a isoform, but not the core function of the canonical mitochondrial TIMM50 protein. Reason: Track as isoform-specific, non-core nuclear localization; canonical TIMM50 function is mitochondrial TIM23 import. Supporting Evidence: PMID:16008839 cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
GO:0043021 ribonucleoprotein complex binding	IDA Q3ZCQ8-2 PMID:16008839 Tim50a, a nuclear isoform of the mitochondrial Tim50, intera...	KEEP AS NON CORE	Summary: Supported for the nuclear Tim50a isoform, which interacts with snRNP-associated proteins, but this is not the canonical mitochondrial import function. Reason: Keep as an isoform-specific non-core activity distinct from TIM23 presequence import. Supporting Evidence: PMID:16008839 In addition to coilin, Tim50a interacts with snRNPs and PMID:16008839 cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
GO:0030943 mitochondrion targeting sequence binding	NAS file:human/TIMM50/TIMM50-deep-research-falcon.md	NEW	Summary: TIMM50 is described as the primary inner-membrane presequence receptor for TIM23 substrates, so mitochondrion targeting sequence binding captures its core molecular function better than generic protein binding. Reason: Existing GOA lacks a specific molecular-function term for TIMM50 presequence/targeting-signal receptor activity. Supporting Evidence: file:human/TIMM50/TIMM50-deep-research-falcon.md Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. file:human/TIMM50/TIMM50-deep-research-falcon.md TIMM50 primarily acts on presequence-containing precursor proteins, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion. file:human/TIMM50/TIMM50-deep-research-falcon.md This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.

Core Functions

TIMM50 is the inner-membrane TIM23 presequence receptor and gatekeeper that captures transit peptide-containing mitochondrial precursors on the intermembrane-space side, coordinates TIM23 channel gating, and supports import into the matrix or IMM sorting pathway.

Molecular Function:

mitochondrion targeting sequence binding

Directly Involved In:

protein import into mitochondrial matrix

Cellular Locations:

mitochondrial inner membrane

In Complex:

TIM23 mitochondrial import inner membrane translocase complex

Supporting Evidence:

file:human/TIMM50/TIMM50-deep-research-falcon.md
Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**, positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and coordinate their entry into TIM23.
file:human/TIMM50/TIMM50-deep-research-falcon.md
TIMM50 primarily acts on **presequence-containing precursor proteins**, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion.
file:human/TIMM50/TIMM50-deep-research-falcon.md
This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported.
file:human/TIMM50/TIMM50-deep-research-falcon.md
TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates receptor/gating functions.

References

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

PMID:10339406

Genetic and structural characterization of the human mitochondrial inner membrane translocase.

PMID:12620389

Novel raf kinase protein-protein interactions found by an exhaustive yeast two-hybrid analysis.

PMID:15044455

Tim50, a component of the mitochondrial translocator, regulates mitochondrial integrity and cell death.

PMID:16008839

Tim50a, a nuclear isoform of the mitochondrial Tim50, interacts with proteins involved in snRNP biogenesis.

PMID:25852190

Integrative analysis of kinase networks in TRAIL-induced apoptosis provides a source of potential targets for combination therapy.

PMID:30598479

ROMO1 is a constituent of the human presequence translocase required for YME1L protease import.

PMID:31980649

Extensive rewiring of the EGFR network in colorectal cancer cells expressing transforming levels of KRAS(G13D).

PMID:32848200

Ttm50 facilitates calpain activation by anchoring it to calcium stores and increasing its sensitivity to calcium.

PMID:34800366

Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.

PMID:37045861

Interactome dynamics of RAF1-BRAF kinase monomers and dimers.

PMID:38828998

Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease.

file:human/TIMM50/TIMM50-deep-research-falcon.md

Falcon deep research report for human TIMM50

Suggested Experiments

Experiment: Use TIMM50 rescue mutants affecting presequence-binding and TIMM23-interaction surfaces in TIMM50-deficient human cells, then measure TIM23 complex assembly, channel gating, and import of TIM23MOTOR versus TIM23SORT reporter substrates.

Hypothesis: TIMM50 presequence binding and channel-gating surfaces are separable.

Experiment: Compare phosphatase-dead TIMM50 mutants with receptor/gating mutants for rescue of matrix import, IMM sorting, TIM23 complex stability, and patient-cell respiratory phenotypes.

Hypothesis: TIMM50 phosphatase-like activity is dispensable for most TIM23 import functions.

Deep Research

Falcon

(TIMM50-deep-research-falcon.md)

TIMM50 (UniProt Q3ZCQ8) Functional Annotation Research Report (Human) Falcon Edison Scientific Literature 38 citations 2026-05-11T16:49:10.112666

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.

TIMM50 (UniProt Q3ZCQ8) Functional Annotation Research Report (Human)

1) Target verification (critical identity check)

The UniProt accession Q3ZCQ8 corresponds to Homo sapiens TIMM50 (Tim50), annotated as mitochondrial import inner membrane translocase subunit TIM50, precursor and belonging to the TIM50 family. Recent primary and review literature consistently places TIMM50 as a core subunit of the mitochondrial inner membrane TIM23 (“presequence”) translocase, together with TIMM23 and TIMM17A/B, confirming that the gene symbol TIMM50 matches the protein description provided and that the organism context is human. (crameri2024reducedproteinimport pages 1-3, paz2024biochemicalandneurophysiological pages 1-2)

2) Key concepts & definitions (current understanding)

2.1 Mitochondrial protein import via TOM and TIM23

Most mitochondrial proteins are encoded in the nucleus and must be imported post-translationally. The TIM23 complex is the major inner-membrane import route for proteins carrying N-terminal, positively charged amphipathic targeting signals (“presequences” / MTSs), delivering clients to the matrix or inserting some clients into the inner mitochondrial membrane (IMM). (paz2024biochemicalandneurophysiological pages 1-2, fielden2023centralroleof pages 1-4)

2.2 TIMM50/Tim50: primary inner-membrane presequence receptor and gate regulator

Tim50 is widely regarded as the primary presequence receptor at the inner membrane, positioned in the intermembrane space (IMS) to receive precursors emerging from the TOM pore and coordinate their entry into TIM23. A foundational mechanistic study mapped presequence contact sites and concluded Tim50 is the primary presequence receptor and that presequences and Tim50 regulate the Tim23 channel antagonistically, consistent with a receptor-plus-gating function. (schulz2011tim50’spresequencereceptor pages 1-2)

2.3 TIM23 modularity: import-to-matrix versus inner-membrane sorting

Human TIM23 exists in at least two functional assemblies:
- TIM23MOTOR, which couples the translocase to the ATP-driven import motor (PAM) to achieve full matrix translocation.
- TIM23SORT, which supports lateral release of hydrophobic segments into the IMM (inner-membrane insertion/sorting).
A 2024 human study operationalized these modules and used them to interpret selective substrate sensitivity in TIMM50 disease. (crameri2024reducedproteinimport pages 1-3)

3) Molecular function, localization, and mechanism

3.1 Subcellular localization and topology

TIMM50 is a single-pass IMM protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed hydrophilic domain that mediates receptor/gating functions. (demishteinzohary2017thetim23mitochondrial pages 3-4, genge2023twodomainsof pages 1-2)

3.2 Core function: substrate class and “substrate specificity”

TIMM50 is not a transporter of small molecules; rather, its substrate specificity is defined by the type of protein precursors it helps import. TIMM50 primarily acts on presequence-containing precursor proteins, which constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix delivery or IMM insertion. (crameri2024reducedproteinimport pages 1-3, paz2024biochemicalandneurophysiological pages 1-2)

3.3 TIMM50 as receptor and gatekeeper (interaction logic)

Mechanistic and review evidence supports the following model:
1. Presequence-containing precursors are recognized at the outer membrane and pass through TOM.
2. On the IMS side, TIMM50/Tim50 captures the presequence as it emerges from TOM.
3. TIMM50 interacts with Tim23 in the IMS and helps regulate channel opening/closure, keeping the pathway closed in the absence of import substrates and switching states upon presequence engagement.
This receptor/gating logic is supported by direct presequence-binding mapping and the conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being transported. (schulz2011tim50’spresequencereceptor pages 1-2, demishteinzohary2017thetim23mitochondrial pages 3-4)

3.4 TOM–TIM23 handover and coupling across two membranes

Tim50 can be cross-linked to precursors arrested at the TOM “trans” site and can contact TOM-side components (classically described for Tim50/Tim23 with Tom22/Tom40 in mechanistic syntheses), supporting the concept of transient TOM–TIM23 cooperation during active translocation. A 2023 domain-dissection study emphasized that Tim50’s IMS domain(s) coordinate TOM–TIM23 cooperation and that the Tim50 core domain contains the main presequence-binding site and recruitment point to TIM23. (genge2023twodomainsof pages 1-2)

3.5 Relationship to 2023 structural revision of the TIM23 channel

Two high-impact 2023 Nature papers reframed the TIM23 mechanism by emphasizing Tim17 as central to the translocation path:
- Cryo-EM of the TIM23 core supports a stable Tim17–Tim23 heterodimer architecture and proposes a laterally open Tim17 cavity, with Mgr2 positioned near a lateral opening. (2023-06; https://doi.org/10.1038/s41586-023-06239-6) (sim2023structuralbasisof pages 1-4)
- In-native-membrane crosslinking mapped preprotein contacts and showed conserved negative charges in Tim17 are essential to initiate presequence translocation along a distinct Tim17 cavity, enabling lateral release for IMM-sorted precursors. (2023-08; https://doi.org/10.1038/s41586-023-06477-8) (fielden2023centralroleof pages 1-4)
These findings do not diminish TIMM50’s receptor role; rather, they shift the likely translocation cavity away from Tim23 alone and toward Tim17, while TIMM50 remains essential for presequence capture, TOM–TIM coordination, and gating control at the IMS face of the machinery. (schulz2011tim50’spresequencereceptor pages 1-2, fielden2023centralroleof pages 1-4)

3.6 Enzymatic/phosphatase-like domain: what is known vs. uncertain

TIMM50 contains a HAD/FCP1-like phosphatase-like fold, and reviews report that human TIMM50 has dual-specificity phosphatase/phosphohydrolase activity, but the physiological substrates and relevance to import are described as unclear/“elusive.” Therefore, based on available evidence, the primary validated function remains protein import receptor/gating, not a defined metabolic reaction with established substrates. (chaudhuri2021diversefunctionsof pages 10-11, chaudhuri2021diversefunctionsof pages 13-15)

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

4.1 2023: structural mechanism of TIM23 and redefinition of channel architecture

The 2023 cryo-EM and functional mapping studies (Nature) are a major recent development because they provide structural constraints on TIM23 stoichiometry and support a model in which Tim17 provides a key transmembrane cavity for presequence protein translocation and lateral release, requiring negatively charged residues near the IMS leaflet. (sim2023structuralbasisof pages 1-4, fielden2023centralroleof pages 1-4)

4.2 2024: TIMM50-associated mitochondrial disease mechanistically linked to TIM23SORT

A 2024 Molecular and Cellular Biology study analyzed patient fibroblasts with a homozygous TIMM50 p.(Arg113Cys) variant and a cellular disease model, and linked TIMM50 dysfunction to reduced TIM23 complex levels/activity and to a selective vulnerability of TIM23SORT (lateral insertion) substrates. (2024-06; https://doi.org/10.1080/10985549.2024.2353652) (crameri2024reducedproteinimport pages 4-5, crameri2024reducedproteinimport pages 11-12)

Quantitative examples from this study (patient cells / import assays):
- TIM23MOTOR substrate OTC import ~82% of control.
- TIM23SORT substrates SURF1 ~67% and SCO2 ~62% of control.
- Total mitochondrial protein content decreased from ~8% to ~6.5% of total cellular protein.
These values support a mechanistic interpretation that TIMM50 loss disproportionately compromises the sorting/lateral insertion arm of TIM23. (crameri2024reducedproteinimport pages 11-12, crameri2024reducedproteinimport pages 4-5)

4.3 2024: biochemical and neurophysiological consequences of TIMM50 deficiency

A 2024 eLife study investigated TIMM50 deficiency in patient fibroblasts and neuronal TIMM50 knockdown models and reported:
- Reduced basal/maximal/ATP-linked respiration and reduced glycolytic capacity/reserve, consistent with impaired energetic flexibility.
- Approximately twofold decrease in the percentage of mobile mitochondria in TIMM50-deficient neurons.
- No effect on mtDNA levels in the tested model systems.
(2024-12; https://doi.org/10.7554/eLife.99914) (paz2024biochemicalandneurophysiological pages 9-11)

4.4 2024: expert synthesis on mutation “hotspots” in TIM23—TIMM50 stands out

A 2024 mini-review reported that among TIM23 complex genes, TIMM50 has the highest number of reported disease-causing mutations, summarizing eight distinct TIMM50 variants and their associated phenotypes. (2024-11; https://doi.org/10.3390/genes15121534) (jain2024hotspotsfordiseasecausing pages 5-7, jain2024hotspotsfordiseasecausing pages 8-9)

5) Current applications and real-world implementations

5.1 Clinical genetics and diagnostic interpretation

TIMM50 is clinically relevant primarily through rare-disease diagnostics for early-onset mitochondrial disorders, including 3-methylglutaconic aciduria type IX (MGCA9) and related encephalopathic phenotypes. A 2024 review summarizes disease-linked variants and common clinical features, providing a starting point for variant prioritization in exome/genome sequencing pipelines. (jain2024hotspotsfordiseasecausing pages 7-8, jain2024hotspotsfordiseasecausing pages 4-5)

5.2 Functional validation in patient-derived cells

Recent work demonstrates a practical diagnostic/interpretive workflow: identify candidate variants, then test for TIMM50 protein loss, TIM23 complex integrity (e.g., BN-PAGE), and TIM23-dependent import defects with defined reporter substrates, including separation of TIM23MOTOR vs TIM23SORT clients. This is a real-world implementation of mechanistic import biology into disease interpretation. (crameri2024reducedproteinimport pages 4-5, crameri2024reducedproteinimport pages 11-12)

5.3 Proteomics for mechanism-of-disease inference

The 2024 TIMM50 study built a proteomic map of TIMM50-associated disease and leveraged substrate-class analysis (TIM23SORT vs TIM23MOTOR) to infer pathway-specific vulnerability, illustrating how proteomics can be used to move from “gene → mechanism” in mitochondrial disorders. (crameri2024reducedproteinimport pages 1-3)

6) Disease associations, phenotypes, and recent statistics/data

6.1 Variant spectrum and phenotype summary

Reported TIMM50 variants include early truncation and multiple missense alleles (e.g., Ser9Ter, Gly87Ala, Arg114Gln/Trp, Thr149Met, Ala222Thr, Arg239Trp, Gly269Ser), with phenotypes including developmental delay/encephalopathy, seizures/epileptic spasms, lactic acidosis, OXPHOS defects, and MGCA9. (jain2024hotspotsfordiseasecausing pages 4-5)

6.2 Visual-system involvement statistic

A 2024 mini-review reported abnormal electroretinograms in ≥60% of individuals with TIMM50 variants, highlighting visual pathway involvement as a recurrent clinical feature. (jain2024hotspotsfordiseasecausing pages 7-8)

6.3 Quantitative cellular phenotypes (recent primary studies)

TIMM50 p.Arg113Cys patient fibroblasts show selective reductions in TIM23SORT import (SURF1 67%, SCO2 62%) relative to a TIM23MOTOR substrate (OTC 82%), and decreased mitochondrial protein content (~8%→~6.5%). (crameri2024reducedproteinimport pages 4-5, crameri2024reducedproteinimport pages 11-12)
TIMM50 deficiency causes measurable bioenergetic impairment and reduced mitochondrial motility (~2-fold reduction in mobile mitochondria) in neuronal models. (paz2024biochemicalandneurophysiological pages 9-11)

7) Expert opinions and authoritative analyses (how experts interpret TIMM50 biology)

7.1 TIMM50 as a mechanistic bridge between TOM and TIM23

Authoritative mechanistic interpretations emphasize TIMM50/Tim50 as an IMS receptor that couples the two membrane translocases by binding presequences and coordinating handover, with its interactions modulated by the incoming signal peptide. (genge2023twodomainsof pages 1-2, demishteinzohary2017thetim23mitochondrial pages 3-4)

7.2 TIMM50 mutation hotspot within TIM23 complex

Expert synthesis argues TIMM50 is a relative hotspot for disease-causing variants among TIM23 components, and that TIMM50 dysfunction can yield severe early-onset neurological disease via impaired protein import. (jain2024hotspotsfordiseasecausing pages 5-7, jain2024hotspotsfordiseasecausing pages 7-8)

7.3 TIMM50 and lateral insertion (TIM23SORT) as a disease mechanism

The 2024 patient-cell proteomics/import data support a more nuanced view: while TIMM50 is classically described as a presequence receptor, TIMM50 loss in humans disproportionately affects TIM23SORT-mediated lateral insertion clients—many of which relate to OXPHOS and mitochondrial ultrastructure—providing a plausible biochemical explanation for specific phenotypes. (crameri2024reducedproteinimport pages 1-3, crameri2024reducedproteinimport pages 11-12)

8) Summary table (evidence-linked)

The following table condenses the functional annotation, interaction network, recent structural advances, and 2024 disease evidence.

Topic	Key points	Representative recent sources (with year)	Citation IDs
Protein identity / topology / domains	Human TIMM50 encodes mitochondrial import inner membrane translocase subunit Tim50 (UniProt Q3ZCQ8), a core TIM23 subunit. It is a single-pass inner mitochondrial membrane protein with an N-terminal mitochondrial targeting sequence, a transmembrane anchor, and a large IMS-exposed receptor domain. Human TIMM50 contains an FCP1-like / HAD-like phosphatase-like core (NIF/HAD fold); unlike fungal Tim50, human TIMM50 lacks the fungal C-terminal PBD, but key groove/β-strand receptor features are conserved.	Crameri et al., 2024; Chaudhuri et al., 2021; Demishtein-Zohary & Azem, 2017	(crameri2024reducedproteinimport pages 1-3, chaudhuri2021diversefunctionsof pages 21-22, chaudhuri2021diversefunctionsof pages 6-7, chaudhuri2021diversefunctionsof pages 10-11, demishteinzohary2017thetim23mitochondrial pages 3-4)
Role in TIM23MOTOR vs TIM23SORT	TIMM50 is part of the TIM23 core with TIMM23 and TIMM17A/B. In TIM23MOTOR, accessory factors such as DNAJC19/15, TIMM44, HSPA9, PAM16, and GRPEL1/2 drive ATP-dependent import of presequence proteins into the matrix. In TIM23SORT, TIMM21 and ROMO1 support lateral insertion of single/dual-pass inner membrane proteins. Recent human disease proteomics indicate TIM23SORT clients are especially sensitive to TIMM50 loss.	Crameri et al., 2024; Paz et al., 2024	(crameri2024reducedproteinimport pages 1-3, paz2024biochemicalandneurophysiological pages 1-2)
Key interaction partners	TIMM50 directly/functionally associates with TIMM23 and TIMM17A/B in the TIM23 core. Crosslinking and mechanistic studies place Tim50 in contact with Tom22/Tom40 at the TOM trans site and with Tim21/TIMM21, linking TOM and TIM23 during precursor handover. TIM23SORT also includes ROMO1; TIM23MOTOR includes the PAM machinery (TIMM44, mtHsp70/HSPA9, DNAJC19/15, PAM16, GRPEL1/2).	Genge et al., 2023; Demishtein-Zohary & Azem, 2017; Crameri et al., 2024	(genge2023twodomainsof pages 1-2, genge2024functionaldissectionof pages 19-22, genge2024functionaldissectionof pages 16-19, demishteinzohary2017thetim23mitochondrial pages 3-4, crameri2024reducedproteinimport pages 1-3)
Mechanistic concept: presequence receptor	Tim50 is the primary presequence receptor at the inner membrane. It recognizes positively charged, amphipathic N-terminal targeting sequences as they emerge from TOM and helps deliver them to the TIM23 translocase. The core IMS domain contains the principal presequence-binding site and is the main recruitment point to the TIM23 complex.	Schulz et al., 2011; Genge et al., 2023	(schulz2011tim50’spresequencereceptor pages 1-2, genge2023twodomainsof pages 1-2)
Mechanistic concept: gating / closure	Tim50 is also a gating regulator: Tim50 binding to Tim23 antagonizes channel opening and helps keep the channel closed in the absence of substrate; presequence engagement relieves this inhibitory state and promotes productive translocation. Reviews describe Tim50/Tim23 as receptor-gating components on the IMS side of the TIM23 complex.	Schulz et al., 2011; Demishtein-Zohary & Azem, 2017	(schulz2011tim50’spresequencereceptor pages 1-2, demishteinzohary2017thetim23mitochondrial pages 3-4)
Mechanistic concept: TOM–TIM23 handover	Tim50 can bind precursor proteins while they are still at/near the TOM trans site and can contact Tom22 and Tom40, supporting a transient TOM–TIM23 supercomplex. Presequence binding modulates Tim50 interactions with Tom22/Tim21 and coordinates handover from TOM to TIM23.	Genge et al., 2023; recent mechanistic syntheses 2024–2025	(genge2023twodomainsof pages 1-2, genge2024functionaldissectionof pages 19-22, genge2024functionaldissectionof pages 16-19, jain2025investigatingmitochondrialpresequence pages 20-23, jain2025investigatingmitochondrialpresequence pages 15-17)
Mechanistic concept: lateral insertion	New mechanistic work shifts emphasis toward Tim17 as the main translocation cavity with a laterally open, negatively charged path, while TIMM50 remains essential upstream for precursor recognition and pathway selection. Human 2024 proteomics suggest TIMM50 dysfunction disproportionately affects TIM23SORT-mediated lateral insertion, implying TIMM50 has a stronger role in sorting than previously appreciated.	Sim et al., 2023; Fielden et al., 2023; Crameri et al., 2024	(sim2023structuralbasisof pages 1-4, fielden2023centralroleof pages 1-4, crameri2024reducedproteinimport pages 1-3)
Enzymatic / phosphatase-like activity	TIMM50 carries a phosphatase-like HAD/FCP1-related fold, and reviews report dual-specificity phosphatase / phosphohydrolase activity for human TIMM50. However, the physiological substrates and in vivo relevance remain unclear, so TIMM50 is functionally annotated primarily as an import receptor/gating subunit rather than a validated metabolic enzyme.	Chaudhuri et al., 2021	(chaudhuri2021diversefunctionsof pages 21-22, chaudhuri2021diversefunctionsof pages 10-11, chaudhuri2021diversefunctionsof pages 13-15)
Evidence types supporting function	Evidence spans photo-crosslinking and receptor mapping (2011), domain dissection and TOM–TIM coordination (2023), cryo-EM/structural reinterpretation of TIM23 architecture (2023), and patient-cell proteomics/import assays (2024). Together these support TIMM50 as an IMS receptor, channel regulator, and determinant of TIM23 complex integrity and substrate selectivity.	Schulz et al., 2011; Sim et al., 2023; Fielden et al., 2023; Genge et al., 2023; Crameri et al., 2024	(schulz2011tim50’spresequencereceptor pages 1-2, sim2023structuralbasisof pages 1-4, fielden2023centralroleof pages 1-4, genge2023twodomainsof pages 1-2, crameri2024reducedproteinimport pages 1-3)
Disease genetics / clinical spectrum	A 2024 mini-review identified 8 distinct human TIMM50 mutations, making TIMM50 the most mutation-enriched TIM23 subunit currently known. Disease is linked to 3-methylglutaconic aciduria type IX (MGCA9) and/or mitochondrial encephalopathy with failure to thrive, developmental delay, seizures/epileptic spasms, visual pathway abnormalities, optic atrophy, and elevated lactate. Abnormal electroretinograms were reported in ≥60% of affected individuals.	Jain et al., 2024; Crameri et al., 2024	(jain2024hotspotsfordiseasecausing pages 7-8, jain2024hotspotsfordiseasecausing pages 4-5, jain2024hotspotsfordiseasecausing pages 5-7, jain2024hotspotsfordiseasecausing pages 8-9, crameri2024reducedproteinimport pages 1-3)
Quantitative findings from 2024 Crameri study	In patient fibroblasts with homozygous p.Arg113Cys, TIMM50 protein was nearly absent; assembled TIM23 complex and core subunits were reduced. Import assays showed TIM23MOTOR substrate OTC at 82% of control, versus TIM23SORT substrates SURF1 at 67% and SCO2 at 62%. Total mitochondrial protein content fell from ~8% to ~6.5% of total cellular protein. TIM22 substrate import was unaffected; WT TIMM50 re-expression partially rescued defects.	Crameri et al., 2024	(crameri2024reducedproteinimport pages 4-5, crameri2024reducedproteinimport pages 11-12)
Quantitative findings from 2024 Paz study	In patient fibroblasts and TIMM50-KD neurons, TIMM50 deficiency reduced basal, maximal, and ATP-linked respiration and lowered glycolytic capacity/reserve without affecting mtDNA copy number. Neuronal imaging showed an approximately 2-fold decrease in the percentage of mobile mitochondria. Reported assays used n=4–6 biological repeats with significant effects.	Paz et al., 2024	(paz2024biochemicalandneurophysiological pages 9-11)

Table: This table summarizes the core functional annotation, mechanistic biology, interaction network, recent structural advances, and 2024 disease evidence for human TIMM50 (UniProt Q3ZCQ8). It is useful as a compact reference linking molecular function to quantitative patient-cell findings and current expert interpretation.

9) Key recent references (URLs & publication dates)

Sim SI et al. “Structural basis of mitochondrial protein import by the TIM23 complex.” Nature (2023-06). https://doi.org/10.1038/s41586-023-06239-6 (sim2023structuralbasisof pages 1-4)
Fielden LF et al. “Central role of Tim17 in mitochondrial presequence protein translocation.” Nature (2023-08). https://doi.org/10.1038/s41586-023-06477-8 (fielden2023centralroleof pages 1-4)
Genge MG et al. “Two domains of Tim50 coordinate translocation of proteins across the two mitochondrial membranes.” Life Science Alliance (2023-09). https://doi.org/10.26508/lsa.202302122 (genge2023twodomainsof pages 1-2)
Crameri JJ et al. “Reduced Protein Import via TIM23SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease.” Molecular and Cellular Biology (2024-06). https://doi.org/10.1080/10985549.2024.2353652 (crameri2024reducedproteinimport pages 1-3)
Paz E et al. “Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein TIMM50.” eLife (2024-12). https://doi.org/10.7554/eLife.99914 (paz2024biochemicalandneurophysiological pages 1-2)
Jain S et al. “Hotspots for Disease-Causing Mutations in the Mitochondrial TIM23 Import Complex.” Genes (2024-11). https://doi.org/10.3390/genes15121534 (jain2024hotspotsfordiseasecausing pages 7-8)
Schulz C et al. “Tim50’s presequence receptor domain is essential for signal driven transport across the TIM23 complex.” J Cell Biol (2011-11). https://doi.org/10.1083/jcb.201105098 (schulz2011tim50’spresequencereceptor pages 1-2)

10) Notes on limitations and open questions

Many mechanistic details (e.g., exact residue-level interaction interfaces between human TIMM50 and TOM/TIM23 components; high-resolution structures of human TOM–TIM23 with substrate in transit) remain incompletely resolved in the available excerpts, and some structural insights are currently derived largely from yeast systems extrapolated to mammals. (sim2023structuralbasisof pages 1-4, genge2023twodomainsof pages 1-2)
Although TIMM50 has a phosphatase-like fold and phosphatase activity has been reported in reviews, clear consensus on in vivo substrates and physiological impact remains lacking; current evidence supports prioritizing its role as an import receptor/gating component. (chaudhuri2021diversefunctionsof pages 10-11, chaudhuri2021diversefunctionsof pages 13-15)

References

(crameri2024reducedproteinimport pages 1-3): Jordan J. Crameri, Catherine S. Palmer, Tegan Stait, Thomas D. Jackson, Matthew Lynch, Adriane Sinclair, Leah E. Frajman, Alison G. Compton, David Coman, David R. Thorburn, Ann E. Frazier, and Diana Stojanovski. Reduced protein import via tim23 sort drives disease pathology in timm50-associated mitochondrial disease. Molecular and Cellular Biology, 44:226-244, Jun 2024. URL: https://doi.org/10.1080/10985549.2024.2353652, doi:10.1080/10985549.2024.2353652. This article has 9 citations and is from a domain leading peer-reviewed journal.
(paz2024biochemicalandneurophysiological pages 1-2): Eyal Paz, Sahil Jain, Irit Gottfried, Orna Staretz-Chacham, Muhammad Mahajnah, Pritha Bagchi, Nicholas T Seyfried, Uri Ashery, and Abdussalam Azem. Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein timm50. eLife, Dec 2024. URL: https://doi.org/10.7554/elife.99914, doi:10.7554/elife.99914. This article has 5 citations and is from a domain leading peer-reviewed journal.
(fielden2023centralroleof pages 1-4): Laura F. Fielden, Jakob D. Busch, Sandra G. Merkt, Iniyan Ganesan, Conny Steiert, Hanna B. Hasselblatt, Jon V. Busto, Christophe Wirth, Nicole Zufall, Sibylle Jungbluth, Katja Noll, Julia M. Dung, Ludmila Butenko, Karina von der Malsburg, Hans-Georg Koch, Carola Hunte, Martin van der Laan, and Nils Wiedemann. Central role of tim17 in mitochondrial presequence protein translocation. Nature, 621:627-634, Aug 2023. URL: https://doi.org/10.1038/s41586-023-06477-8, doi:10.1038/s41586-023-06477-8. This article has 64 citations and is from a highest quality peer-reviewed journal.
(schulz2011tim50’spresequencereceptor pages 1-2): Christian Schulz, Oleksandr Lytovchenko, Jonathan Melin, Agnieszka Chacinska, Bernard Guiard, Piotr Neumann, Ralf Ficner, Olaf Jahn, Bernhard Schmidt, and Peter Rehling. Tim50’s presequence receptor domain is essential for signal driven transport across the tim23 complex. The Journal of Cell Biology, 195:643-656, Nov 2011. URL: https://doi.org/10.1083/jcb.201105098, doi:10.1083/jcb.201105098. This article has 117 citations.
(demishteinzohary2017thetim23mitochondrial pages 3-4): Keren Demishtein-Zohary and Abdussalam Azem. The tim23 mitochondrial protein import complex: function and dysfunction. Cell and Tissue Research, 367:33-41, Sep 2017. URL: https://doi.org/10.1007/s00441-016-2486-7, doi:10.1007/s00441-016-2486-7. This article has 59 citations and is from a peer-reviewed journal.
(genge2023twodomainsof pages 1-2): Marcel G Genge, Shalini Roy Chowdhury, Vít Dohnálek, Kaori Yunoki, Takashi Hirashima, Toshiya Endo, Pavel Doležal, and Dejana Mokranjac. Two domains of tim50 coordinate translocation of proteins across the two mitochondrial membranes. Life Science Alliance, 6:e202302122, Sep 2023. URL: https://doi.org/10.26508/lsa.202302122, doi:10.26508/lsa.202302122. This article has 8 citations and is from a peer-reviewed journal.
(sim2023structuralbasisof pages 1-4): Sue Im Sim, Yuanyuan Chen, Diane L. Lynch, James C. Gumbart, and Eunyong Park. Structural basis of mitochondrial protein import by the tim23 complex. Nature, 621:620-626, Jun 2023. URL: https://doi.org/10.1038/s41586-023-06239-6, doi:10.1038/s41586-023-06239-6. This article has 105 citations and is from a highest quality peer-reviewed journal.
(chaudhuri2021diversefunctionsof pages 10-11): Minu Chaudhuri, Anuj Tripathi, and Fidel Soto Gonzalez. Diverse functions of tim50, a component of the mitochondrial inner membrane protein translocase. International Journal of Molecular Sciences, 22:7779, Jul 2021. URL: https://doi.org/10.3390/ijms22157779, doi:10.3390/ijms22157779. This article has 16 citations.
(chaudhuri2021diversefunctionsof pages 13-15): Minu Chaudhuri, Anuj Tripathi, and Fidel Soto Gonzalez. Diverse functions of tim50, a component of the mitochondrial inner membrane protein translocase. International Journal of Molecular Sciences, 22:7779, Jul 2021. URL: https://doi.org/10.3390/ijms22157779, doi:10.3390/ijms22157779. This article has 16 citations.
(crameri2024reducedproteinimport pages 4-5): Jordan J. Crameri, Catherine S. Palmer, Tegan Stait, Thomas D. Jackson, Matthew Lynch, Adriane Sinclair, Leah E. Frajman, Alison G. Compton, David Coman, David R. Thorburn, Ann E. Frazier, and Diana Stojanovski. Reduced protein import via tim23 sort drives disease pathology in timm50-associated mitochondrial disease. Molecular and Cellular Biology, 44:226-244, Jun 2024. URL: https://doi.org/10.1080/10985549.2024.2353652, doi:10.1080/10985549.2024.2353652. This article has 9 citations and is from a domain leading peer-reviewed journal.
(crameri2024reducedproteinimport pages 11-12): Jordan J. Crameri, Catherine S. Palmer, Tegan Stait, Thomas D. Jackson, Matthew Lynch, Adriane Sinclair, Leah E. Frajman, Alison G. Compton, David Coman, David R. Thorburn, Ann E. Frazier, and Diana Stojanovski. Reduced protein import via tim23 sort drives disease pathology in timm50-associated mitochondrial disease. Molecular and Cellular Biology, 44:226-244, Jun 2024. URL: https://doi.org/10.1080/10985549.2024.2353652, doi:10.1080/10985549.2024.2353652. This article has 9 citations and is from a domain leading peer-reviewed journal.
(paz2024biochemicalandneurophysiological pages 9-11): Eyal Paz, Sahil Jain, Irit Gottfried, Orna Staretz-Chacham, Muhammad Mahajnah, Pritha Bagchi, Nicholas T Seyfried, Uri Ashery, and Abdussalam Azem. Biochemical and neurophysiological effects of deficiency of the mitochondrial import protein timm50. eLife, Dec 2024. URL: https://doi.org/10.7554/elife.99914, doi:10.7554/elife.99914. This article has 5 citations and is from a domain leading peer-reviewed journal.
(jain2024hotspotsfordiseasecausing pages 5-7): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(jain2024hotspotsfordiseasecausing pages 8-9): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(jain2024hotspotsfordiseasecausing pages 7-8): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(jain2024hotspotsfordiseasecausing pages 4-5): Sahil Jain, Eyal Paz, and Abdussalam Azem. Hotspots for disease-causing mutations in the mitochondrial tim23 import complex. Genes, 15:1534, Nov 2024. URL: https://doi.org/10.3390/genes15121534, doi:10.3390/genes15121534. This article has 1 citations.
(chaudhuri2021diversefunctionsof pages 21-22): Minu Chaudhuri, Anuj Tripathi, and Fidel Soto Gonzalez. Diverse functions of tim50, a component of the mitochondrial inner membrane protein translocase. International Journal of Molecular Sciences, 22:7779, Jul 2021. URL: https://doi.org/10.3390/ijms22157779, doi:10.3390/ijms22157779. This article has 16 citations.
(chaudhuri2021diversefunctionsof pages 6-7): Minu Chaudhuri, Anuj Tripathi, and Fidel Soto Gonzalez. Diverse functions of tim50, a component of the mitochondrial inner membrane protein translocase. International Journal of Molecular Sciences, 22:7779, Jul 2021. URL: https://doi.org/10.3390/ijms22157779, doi:10.3390/ijms22157779. This article has 16 citations.
(genge2024functionaldissectionof pages 19-22): Marcel Gilbert Genge. Functional dissection of the two domains of tim50, the main receptor of the tim23 complex. Dissertation, Jan 2024. URL: https://doi.org/10.5282/edoc.34256, doi:10.5282/edoc.34256. This article has 0 citations.
(genge2024functionaldissectionof pages 16-19): Marcel Gilbert Genge. Functional dissection of the two domains of tim50, the main receptor of the tim23 complex. Dissertation, Jan 2024. URL: https://doi.org/10.5282/edoc.34256, doi:10.5282/edoc.34256. This article has 0 citations.
(jain2025investigatingmitochondrialpresequence pages 20-23): Naintara Jain. Investigating Mitochondrial Presequence Import. PhD thesis, University Goettingen, 2025. URL: https://doi.org/10.53846/goediss-11596, doi:10.53846/goediss-11596.
(jain2025investigatingmitochondrialpresequence pages 15-17): Naintara Jain. Investigating Mitochondrial Presequence Import. PhD thesis, University Goettingen, 2025. URL: https://doi.org/10.53846/goediss-11596, doi:10.53846/goediss-11596.

Citations

crameri2024reducedproteinimport pages 1-3
genge2023twodomainsof pages 1-2
sim2023structuralbasisof pages 1-4
fielden2023centralroleof pages 1-4
paz2024biochemicalandneurophysiological pages 9-11
jain2024hotspotsfordiseasecausing pages 4-5
jain2024hotspotsfordiseasecausing pages 7-8
paz2024biochemicalandneurophysiological pages 1-2
chaudhuri2021diversefunctionsof pages 10-11
chaudhuri2021diversefunctionsof pages 13-15
crameri2024reducedproteinimport pages 4-5
crameri2024reducedproteinimport pages 11-12
jain2024hotspotsfordiseasecausing pages 5-7
jain2024hotspotsfordiseasecausing pages 8-9
chaudhuri2021diversefunctionsof pages 21-22
chaudhuri2021diversefunctionsof pages 6-7
genge2024functionaldissectionof pages 19-22
genge2024functionaldissectionof pages 16-19
jain2025investigatingmitochondrialpresequence pages 20-23
jain2025investigatingmitochondrialpresequence pages 15-17
https://doi.org/10.1038/s41586-023-06239-6
https://doi.org/10.1038/s41586-023-06477-8
https://doi.org/10.1080/10985549.2024.2353652
https://doi.org/10.7554/eLife.99914
https://doi.org/10.3390/genes15121534
https://doi.org/10.26508/lsa.202302122
https://doi.org/10.1083/jcb.201105098
https://doi.org/10.1080/10985549.2024.2353652,
https://doi.org/10.7554/elife.99914,
https://doi.org/10.1038/s41586-023-06477-8,
https://doi.org/10.1083/jcb.201105098,
https://doi.org/10.1007/s00441-016-2486-7,
https://doi.org/10.26508/lsa.202302122,
https://doi.org/10.1038/s41586-023-06239-6,
https://doi.org/10.3390/ijms22157779,
https://doi.org/10.3390/genes15121534,
https://doi.org/10.5282/edoc.34256,
https://doi.org/10.53846/goediss-11596,

📄 View Raw YAML

id: Q3ZCQ8
gene_symbol: TIMM50
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: 'TIMM50 encodes the single-pass mitochondrial inner membrane Tim50 subunit of the TIM23 presequence
  translocase. TIMM50 acts from the intermembrane-space side as a primary presequence receptor and gatekeeper for
  TIM23-dependent import of transit peptide-containing precursor proteins, while its reported phosphatase, nuclear
  Tim50a, and calpain-associated roles are secondary or insufficiently established as core human TIMM50 functions.'
alternative_products:
- name: '1'
  id: Q3ZCQ8-1
- name: 2 (Tim50a)
  id: Q3ZCQ8-2
  sequence_note: VSP_016389
- name: '3'
  id: Q3ZCQ8-3
  sequence_note: VSP_047682, VSP_047683
existing_annotations:
- term:
    id: GO:0030150
    label: protein import into mitochondrial matrix
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Correct and core. TIMM50 is the TIM23 presequence receptor/gatekeeper needed for import of
      transit peptide-containing precursors through the inner membrane toward the matrix or IMM sorting
      pathway.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 primarily acts on **presequence-containing precursor proteins**, which
        constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway
        for matrix delivery or IMM insertion.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005744
    label: TIM23 mitochondrial import inner membrane translocase complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence
      handoff and channel gating.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
    - reference_id: PMID:15044455
      supporting_text: complex with human Tim23. Down-regulation of human Tim50 expression by RNA
- term:
    id: GO:0004722
    label: protein serine/threonine phosphatase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological
      substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23
      presequence receptor/gatekeeper.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    - PMID:15044455
    reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no
      established physiological substrate in the import pathway.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: demonstrate that human Tim50 possesses phosphatase activity and is present in a
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Therefore, based on available evidence, the primary validated function remains
        **protein import receptor/gating**, not a defined metabolic reaction with established substrates.
- term:
    id: GO:0005743
    label: mitochondrial inner membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its
      receptor/gating domain exposed to the intermembrane space.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0016607
    label: nuclear speck
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: Supported for the Tim50a isoform, but not the core function of the canonical mitochondrial TIMM50
      protein.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - PMID:16008839
    reason: Track as isoform-specific, non-core nuclear localization; canonical TIMM50 function is
      mitochondrial TIM23 import.
    supported_by:
    - reference_id: PMID:16008839
      supporting_text: cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
  isoform: Q3ZCQ8-2
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:12620389
  review:
    summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction
      context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Replace generic interaction capture with TIM23 complex membership and
      presequence/targeting-sequence binding where supported.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25852190
  review:
    summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction
      context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Replace generic interaction capture with TIM23 complex membership and
      presequence/targeting-sequence binding where supported.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31980649
  review:
    summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction
      context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Replace generic interaction capture with TIM23 complex membership and
      presequence/targeting-sequence binding where supported.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:37045861
  review:
    summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction
      context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Replace generic interaction capture with TIM23 complex membership and
      presequence/targeting-sequence binding where supported.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005743
    label: mitochondrial inner membrane
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its
      receptor/gating domain exposed to the intermembrane space.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0005743
    label: mitochondrial inner membrane
  evidence_type: NAS
  original_reference_id: PMID:10339406
  review:
    summary: Correct. Canonical TIMM50 is a single-pass mitochondrial inner membrane protein with its
      receptor/gating domain exposed to the intermembrane space.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0005744
    label: TIM23 mitochondrial import inner membrane translocase complex
  evidence_type: NAS
  original_reference_id: PMID:10339406
  review:
    summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence
      handoff and channel gating.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
    - reference_id: PMID:15044455
      supporting_text: complex with human Tim23. Down-regulation of human Tim50 expression by RNA
- term:
    id: GO:0006886
    label: intracellular protein transport
  evidence_type: NAS
  original_reference_id: PMID:10339406
  review:
    summary: Correct pathway family but too broad. TIMM50 specifically mediates TIM23-dependent mitochondrial
      presequence protein import rather than general intracellular protein transport.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Use mitochondrial matrix import/TIM23 terms instead of generic intracellular transport.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 primarily acts on **presequence-containing precursor proteins**, which
        constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway
        for matrix delivery or IMM insertion.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: Broad nuclear localization is less informative than the isoform-specific nuclear speck evidence
      for Tim50a and is not the canonical TIMM50 localization.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - PMID:16008839
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Use isoform-specific nuclear speck annotation for Tim50a; canonical TIMM50 is an inner
      mitochondrial membrane TIM23 subunit.
    supported_by:
    - reference_id: PMID:16008839
      supporting_text: cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex
      subunit.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0030150
    label: protein import into mitochondrial matrix
  evidence_type: IDA
  original_reference_id: PMID:38828998
  review:
    summary: Correct and core. TIMM50 is the TIM23 presequence receptor/gatekeeper needed for import of
      transit peptide-containing precursors through the inner membrane toward the matrix or IMM sorting
      pathway.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 primarily acts on **presequence-containing precursor proteins**, which
        constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway
        for matrix delivery or IMM insertion.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: HTP
  original_reference_id: PMID:34800366
  review:
    summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex
      subunit.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0005744
    label: TIM23 mitochondrial import inner membrane translocase complex
  evidence_type: IDA
  original_reference_id: PMID:30598479
  review:
    summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence
      handoff and channel gating.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
    - reference_id: PMID:15044455
      supporting_text: complex with human Tim23. Down-regulation of human Tim50 expression by RNA
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: PMID:32848200
  review:
    summary: Correct but broad. Canonical TIMM50 is specifically an inner mitochondrial membrane TIM23 complex
      subunit.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Prefer mitochondrial inner membrane and TIM23 complex annotations over generic mitochondrion.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
        sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
        receptor/gating functions.
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IDA
  original_reference_id: PMID:32848200
  review:
    summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store
      context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - PMID:32848200
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical
      Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human
      TIMM50-specific support.
    supported_by:
    - reference_id: PMID:32848200
      supporting_text: GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that
    - reference_id: PMID:32848200
      supporting_text: stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain
    - reference_id: PMID:32848200
      supporting_text: magnitude. Our findings reveal the regulation of calpain activation by Ttm50,
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0005794
    label: Golgi apparatus
  evidence_type: IDA
  original_reference_id: PMID:32848200
  review:
    summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store
      context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - PMID:32848200
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical
      Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human
      TIMM50-specific support.
    supported_by:
    - reference_id: PMID:32848200
      supporting_text: GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that
    - reference_id: PMID:32848200
      supporting_text: stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain
    - reference_id: PMID:32848200
      supporting_text: magnitude. Our findings reveal the regulation of calpain activation by Ttm50,
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0140608
    label: cysteine-type endopeptidase activator activity
  evidence_type: IDA
  original_reference_id: PMID:32848200
  review:
    summary: The cited FlyBase-sourced study supports a Drosophila Ttm50 calpain/ER-Golgi calcium-store
      context, but the human TIMM50 synthesis supports mitochondrial TIM23 import as the established function.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - PMID:32848200
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: PMID:32848200 studies Drosophila Ttm50, not human TIMM50. Do not treat the noncanonical
      Ttm50 calpain calcium-store finding as a core human TIMM50 activity or localization without human
      TIMM50-specific support.
    supported_by:
    - reference_id: PMID:32848200
      supporting_text: GluRIIA at the Drosophila neuromuscular junction as a readout, we uncovered that
    - reference_id: PMID:32848200
      supporting_text: stores Golgi and endoplasmic reticulum (ER), and Ttm50 interacts with calpain
    - reference_id: PMID:32848200
      supporting_text: magnitude. Our findings reveal the regulation of calpain activation by Ttm50,
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0001836
    label: release of cytochrome c from mitochondria
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: Supported as a downstream consequence of TIMM50 depletion and mitochondrial membrane dysfunction,
      but it is not the core molecular/cellular role of TIMM50.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - PMID:15044455
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: TIMM50 loss can accelerate cytochrome c release, but TIMM50 itself is primarily a TIM23 import
      receptor/gatekeeper.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: accelerating the release of cytochrome c from the mitochondria. Furthermore,
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0004721
    label: phosphoprotein phosphatase activity
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological
      substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23
      presequence receptor/gatekeeper.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    - PMID:15044455
    reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no
      established physiological substrate in the import pathway.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: demonstrate that human Tim50 possesses phosphatase activity and is present in a
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Therefore, based on available evidence, the primary validated function remains
        **protein import receptor/gating**, not a defined metabolic reaction with established substrates.
- term:
    id: GO:0005134
    label: interleukin-2 receptor binding
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: The cited Tim50 paper and Falcon synthesis do not support an interleukin-2 receptor binding
      activity for TIMM50; the established molecular role is TIM23 presequence receptor/gating.
    action: REMOVE
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: PMID:15044455 describes human Tim50 as a mitochondrial translocator/TIM23-associated protein
      and contains no mention of IL-2 receptor binding. This annotation appears to be a database
      misattribution, because a mitochondrial inner-membrane translocase subunit is not expected to function
      as an IL-2 receptor ligand or receptor-binding protein.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Therefore, based on available evidence, the primary validated function remains
        **protein import receptor/gating**, not a defined metabolic reaction with established substrates.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0005744
    label: TIM23 mitochondrial import inner membrane translocase complex
  evidence_type: IPI
  original_reference_id: PMID:15044455
  review:
    summary: Correct and core. TIMM50 is a core TIM23 complex subunit that directly coordinates presequence
      handoff and channel gating.
    action: ACCEPT
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
    - reference_id: PMID:15044455
      supporting_text: complex with human Tim23. Down-regulation of human Tim50 expression by RNA
- term:
    id: GO:0004722
    label: protein serine/threonine phosphatase activity
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological
      substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23
      presequence receptor/gatekeeper.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    - PMID:15044455
    reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no
      established physiological substrate in the import pathway.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: demonstrate that human Tim50 possesses phosphatase activity and is present in a
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Therefore, based on available evidence, the primary validated function remains
        **protein import receptor/gating**, not a defined metabolic reaction with established substrates.
- term:
    id: GO:0004725
    label: protein tyrosine phosphatase activity
  evidence_type: IDA
  original_reference_id: PMID:15044455
  review:
    summary: Direct assays reported phosphatase activity, but current synthesis indicates the physiological
      substrate and in vivo relevance remain unclear; TIMM50 should be curated primarily as a TIM23
      presequence receptor/gatekeeper.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    - PMID:15044455
    reason: The phosphatase activity is not the core validated biological function of TIMM50 and has no
      established physiological substrate in the import pathway.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: demonstrate that human Tim50 possesses phosphatase activity and is present in a
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Therefore, based on available evidence, the primary validated function remains
        **protein import receptor/gating**, not a defined metabolic reaction with established substrates.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:15044455
  review:
    summary: Protein binding is true but uninformative for TIMM50. The biologically meaningful interaction
      context is TIM23 presequence receptor/gating and TIMM23/TIM17 complex membership.
    action: MARK_AS_OVER_ANNOTATED
    additional_reference_ids:
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Replace generic interaction capture with TIM23 complex membership and
      presequence/targeting-sequence binding where supported.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
- term:
    id: GO:0007006
    label: mitochondrial membrane organization
  evidence_type: IMP
  original_reference_id: PMID:15044455
  review:
    summary: Supported as a cellular consequence of TIMM50 loss causing mitochondrial membrane
      permeabilization/dysfunction, but it is downstream of the core TIM23 import role.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - PMID:15044455
    - file:human/TIMM50/TIMM50-deep-research-falcon.md
    reason: Keep as non-core because membrane organization phenotypes arise from impaired mitochondrial
      import/integrity rather than a direct membrane-organizing function.
    supported_by:
    - reference_id: PMID:15044455
      supporting_text: indicate that loss of Tim50 in vertebrates causes mitochondrial membrane
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
- term:
    id: GO:0016607
    label: nuclear speck
  evidence_type: IDA
  original_reference_id: PMID:16008839
  review:
    summary: Supported for the Tim50a isoform, but not the core function of the canonical mitochondrial TIMM50
      protein.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - PMID:16008839
    reason: Track as isoform-specific, non-core nuclear localization; canonical TIMM50 function is
      mitochondrial TIM23 import.
    supported_by:
    - reference_id: PMID:16008839
      supporting_text: cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
  isoform: Q3ZCQ8-2
- term:
    id: GO:0043021
    label: ribonucleoprotein complex binding
  evidence_type: IDA
  original_reference_id: PMID:16008839
  review:
    summary: Supported for the nuclear Tim50a isoform, which interacts with snRNP-associated proteins, but
      this is not the canonical mitochondrial import function.
    action: KEEP_AS_NON_CORE
    additional_reference_ids:
    - PMID:16008839
    reason: Keep as an isoform-specific non-core activity distinct from TIM23 presequence import.
    supported_by:
    - reference_id: PMID:16008839
      supporting_text: In addition to coilin, Tim50a interacts with snRNPs and
    - reference_id: PMID:16008839
      supporting_text: cytoplasm and mitochondria, Tim50a is strictly nuclear and is enriched in
  isoform: Q3ZCQ8-2
- term:
    id: GO:0030943
    label: mitochondrion targeting sequence binding
  evidence_type: NAS
  original_reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
  review:
    summary: TIMM50 is described as the primary inner-membrane presequence receptor for TIM23 substrates, so
      mitochondrion targeting sequence binding captures its core molecular function better than generic
      protein binding.
    action: NEW
    reason: Existing GOA lacks a specific molecular-function term for TIMM50 presequence/targeting-signal
      receptor activity.
    supported_by:
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
        positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
        coordinate their entry into TIM23.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: TIMM50 primarily acts on **presequence-containing precursor proteins**, which
        constitute a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway
        for matrix delivery or IMM insertion.
    - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
      supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
        conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
        transported.
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping,
    accompanied by conservative changes to GO terms applied by UniProt
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: PMID:10339406
  title: Genetic and structural characterization of the human mitochondrial inner membrane translocase.
  findings: []
- id: PMID:12620389
  title: Novel raf kinase protein-protein interactions found by an exhaustive yeast two-hybrid analysis.
  findings: []
- id: PMID:15044455
  title: Tim50, a component of the mitochondrial translocator, regulates mitochondrial integrity and cell
    death.
  findings: []
- id: PMID:16008839
  title: Tim50a, a nuclear isoform of the mitochondrial Tim50, interacts with proteins involved in snRNP
    biogenesis.
  findings: []
- id: PMID:25852190
  title: Integrative analysis of kinase networks in TRAIL-induced apoptosis provides a source of potential
    targets for combination therapy.
  findings: []
- id: PMID:30598479
  title: ROMO1 is a constituent of the human presequence translocase required for YME1L protease import.
  findings: []
- id: PMID:31980649
  title: Extensive rewiring of the EGFR network in colorectal cancer cells expressing transforming levels of
    KRAS(G13D).
  findings: []
- id: PMID:32848200
  title: Ttm50 facilitates calpain activation by anchoring it to calcium stores and increasing its sensitivity
    to calcium.
  findings: []
- id: PMID:34800366
  title: Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.
  findings: []
- id: PMID:37045861
  title: Interactome dynamics of RAF1-BRAF kinase monomers and dimers.
  findings: []
- id: PMID:38828998
  title: Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial
    Disease.
  findings: []
- id: file:human/TIMM50/TIMM50-deep-research-falcon.md
  title: Falcon deep research report for human TIMM50
  findings: []
core_functions:
- description: TIMM50 is the inner-membrane TIM23 presequence receptor and gatekeeper that captures transit
    peptide-containing mitochondrial precursors on the intermembrane-space side, coordinates TIM23 channel
    gating, and supports import into the matrix or IMM sorting pathway.
  supported_by:
  - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
    supporting_text: Tim50 is widely regarded as the **primary presequence receptor at the inner membrane**,
      positioned in the **intermembrane space (IMS)** to receive precursors emerging from the TOM pore and
      coordinate their entry into TIM23.
  - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
    supporting_text: TIMM50 primarily acts on **presequence-containing precursor proteins**, which constitute
      a large fraction of the mitochondrial proteome and are imported through the TIM23 pathway for matrix
      delivery or IMM insertion.
  - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
    supporting_text: This receptor/gating logic is supported by direct presequence-binding mapping and the
      conclusion that Tim50 binding to Tim23 can induce channel closure when no substrate is being
      transported.
  - reference_id: file:human/TIMM50/TIMM50-deep-research-falcon.md
    supporting_text: TIMM50 is a **single-pass IMM protein** with an N-terminal mitochondrial targeting
      sequence, a transmembrane anchor, and a large **IMS-exposed hydrophilic domain** that mediates
      receptor/gating functions.
  molecular_function:
    id: GO:0030943
    label: mitochondrion targeting sequence binding
  directly_involved_in:
  - id: GO:0030150
    label: protein import into mitochondrial matrix
  locations:
  - id: GO:0005743
    label: mitochondrial inner membrane
  in_complex:
    id: GO:0005744
    label: TIM23 mitochondrial import inner membrane translocase complex
proposed_new_terms: []
suggested_questions:
- question: What are the physiological substrates, if any, of the TIMM50 phosphatase-like domain in human
    cells?
  experts: []
- question: Which human TIM23SORT substrates depend most strongly on TIMM50 presequence recognition or gating?
  experts: []
- question: Is the Tim50a nuclear speck/snRNP role broadly physiological or restricted to specific transformed
    or neural cell contexts?
  experts: []
suggested_experiments:
- hypothesis: TIMM50 presequence binding and channel-gating surfaces are separable.
  description: Use TIMM50 rescue mutants affecting presequence-binding and TIMM23-interaction surfaces in
    TIMM50-deficient human cells, then measure TIM23 complex assembly, channel gating, and import of
    TIM23MOTOR versus TIM23SORT reporter substrates.
- hypothesis: TIMM50 phosphatase-like activity is dispensable for most TIM23 import functions.
  description: Compare phosphatase-dead TIMM50 mutants with receptor/gating mutants for rescue of matrix
    import, IMM sorting, TIM23 complex stability, and patient-cell respiratory phenotypes.

TIMM50

Gene Description

Existing Annotations Review

Core Functions

TIMM50 is the inner-membrane TIM23 presequence receptor and gatekeeper that captures transit peptide-containing mitochondrial precursors on the intermembrane-space side, coordinates TIM23 channel gating, and supports import into the matrix or IMM sorting pathway.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

TIMM50 (UniProt Q3ZCQ8) Functional Annotation Research Report (Human)

1) Target verification (critical identity check)

2) Key concepts & definitions (current understanding)

2.1 Mitochondrial protein import via TOM and TIM23

2.2 TIMM50/Tim50: primary inner-membrane presequence receptor and gate regulator

2.3 TIM23 modularity: import-to-matrix versus inner-membrane sorting

3) Molecular function, localization, and mechanism

3.1 Subcellular localization and topology

3.2 Core function: substrate class and “substrate specificity”

3.3 TIMM50 as receptor and gatekeeper (interaction logic)

3.4 TOM–TIM23 handover and coupling across two membranes

3.5 Relationship to 2023 structural revision of the TIM23 channel

3.6 Enzymatic/phosphatase-like domain: what is known vs. uncertain

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

4.1 2023: structural mechanism of TIM23 and redefinition of channel architecture

4.2 2024: TIMM50-associated mitochondrial disease mechanistically linked to TIM23SORT

4.3 2024: biochemical and neurophysiological consequences of TIMM50 deficiency

4.4 2024: expert synthesis on mutation “hotspots” in TIM23—TIMM50 stands out

5) Current applications and real-world implementations

5.1 Clinical genetics and diagnostic interpretation

5.2 Functional validation in patient-derived cells

5.3 Proteomics for mechanism-of-disease inference

6) Disease associations, phenotypes, and recent statistics/data

6.1 Variant spectrum and phenotype summary

6.2 Visual-system involvement statistic

6.3 Quantitative cellular phenotypes (recent primary studies)

7) Expert opinions and authoritative analyses (how experts interpret TIMM50 biology)

7.1 TIMM50 as a mechanistic bridge between TOM and TIM23

7.2 TIMM50 mutation hotspot within TIM23 complex

7.3 TIMM50 and lateral insertion (TIM23SORT) as a disease mechanism

8) Summary table (evidence-linked)

9) Key recent references (URLs & publication dates)

10) Notes on limitations and open questions

Citations

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