Proposed New Ontology Terms

peptidyl-lysine lactylation

Definition: A peptidyl-lysine modification process in which a lactyl group is covalently added to the epsilon-amino group of a lysine residue within a protein.

Justification: GO:0141207 captures the ATP-dependent molecular activity but no current biological process term captures its immediate protein-modification outcome. The proposed term should be placed under GO:0018205 peptidyl-lysine modification and related to the broader GO:0043543 protein acylation branch; it would support curation of AARS2 and other experimentally established lysine lactylation mechanisms without conflating them with downstream signaling phenotypes. A live QuickGO ontology search on 2026-08-08 found related delactylase activities but no peptidyl-lysine lactylation biological-process term.

Parent term: peptidyl-lysine modification

Supporting Evidence:

PMID:38163844 : AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b) via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005739 mitochondrion	IBA GO_REF:0000033	ACCEPT	Summary: IBA assignment of AARS2 activity in mitochondria, independently supported by mitochondrial import, enzymology, proteomics, and hypoxia-response studies. Reason: Mitochondria are the established execution site for AARS2's canonical tRNA aminoacylation and editing functions and for its hypoxia-responsive lactylation of mitochondrial substrates. Propagation Review Root cause: NO FAILURE CORE
GO:0070143 mitochondrial alanyl-tRNA aminoacylation	IBA GO_REF:0000033	ACCEPT	Summary: IBA assignment of the mitochondrial alanine-charging process, corroborated by direct recombinant-enzyme assays and rescue of defective mt-tRNA(Ala) charging in human cybrids. Reason: This is the organelle-specific core process executed by AARS2 and is at the appropriate GO granularity. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:30262995 This indicated that AARS2 improved the aminoacylation activity in the case of m.5655A>G, rather than having a stabilizing effect on the tRNA structure.
GO:0004813 alanine-tRNA ligase activity	IBA GO_REF:0000033	ACCEPT	Summary: IBA assignment of substrate-specific alanine-tRNA ligase activity, directly confirmed for purified human mitochondrial AlaRS and in human-cell tRNA-charging rescue experiments. Reason: Alanine-tRNA ligase activity is AARS2's principal conserved molecular function. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:30262995 This indicated that AARS2 improved the aminoacylation activity in the case of m.5655A>G, rather than having a stabilizing effect on the tRNA structure.
GO:0002161 aminoacyl-tRNA deacylase activity	IBA GO_REF:0000033	ACCEPT	Summary: IBA assignment of the broad aminoacyl-tRNA deacylase activity, supported by direct human AARS2 proofreading studies of mischarged Ser-tRNA(Ala) and Gly-tRNA(Ala). Reason: This IBA source term is a true broad proofreading activity independently corroborated by direct human assays of both Ser-tRNA(Ala) and Gly-tRNA(Ala). Retaining the parent accurately represents the family-level inference, while the appended substrate-specific NEW rows separately capture the direct evidence. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:29228266 We demonstrate here that the human mitochondrial AlaRS is capable of editing mischarged tRNAs in vitro PMID:30952159 Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla (Figure 5F).
GO:0000166 nucleotide binding	IEA GO_REF:0000002	MODIFY	Summary: InterPro inference of generic nucleotide binding from conserved AlaRS domains; the physiologically relevant nucleotide substrate is ATP. Reason: Nucleotide binding is true but too broad. Human AARS2 uses ATP for alanine activation and for its conditional lactyltransferase reaction, so ATP binding is the informative replacement. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: ATP binding
GO:0003676 nucleic acid binding	IEA GO_REF:0000002	MODIFY	Summary: InterPro inference of generic nucleic-acid binding; AARS2's established physiological nucleic-acid ligand is mitochondrial tRNA(Ala). Reason: Replace the uninformative parent with tRNA binding, which is directly supported by biochemical dissection of human mitochondrial AlaRS recognition of mt-tRNA(Ala). Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: tRNA binding
GO:0004812 aminoacyl-tRNA ligase activity	IEA GO_REF:0000002	MODIFY	Summary: InterPro inference of broad aminoacyl-tRNA ligase activity from an aaRS additional domain. Reason: The activity class is correct, but alanine specificity is firmly established for AARS2 and should be stated explicitly. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: alanine-tRNA ligase activity
GO:0004813 alanine-tRNA ligase activity	IEA GO_REF:0000120	ACCEPT	Summary: Convergent ARBA, UniRule, InterPro, EC 6.1.1.7, and RHEA:12540 assignment of alanine-tRNA ligase activity. Reason: The electronic mapping exactly matches the directly characterized core reaction of human mitochondrial AlaRS. Propagation Review Root cause: NO FAILURE CORE
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: Electronic ATP-binding assignment from conserved AlaRS catalytic domains and UniRule. Reason: ATP is required to form the aminoacyl-adenylate intermediate in alanine charging and is also required by the conditional lactyltransferase reaction. Propagation Review Root cause: NO FAILURE CORE
GO:0005737 cytoplasm	IEA GO_REF:0000002	MODIFY	Summary: InterPro assigns the broad cellular-component term cytoplasm from AlaRS domains. Because GO cytoplasm includes organelles, the row is not false, but it is needlessly broad for this mitochondrial enzyme. Reason: Replace this parent location with mitochondrion, the established core location of mature AARS2. Hypoxia studies detected a contextual cytosolic pool, but this IEA carries no such condition and should not be taken as evidence for constitutive cytosolic availability. The route by which mitochondrial AARS2 reaches cGAS in the lactate-response study remains unresolved. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: mitochondrion
GO:0005739 mitochondrion	IEA GO_REF:0000044	ACCEPT	Summary: UniProt subcellular-location mapping places AARS2 in mitochondria, consistent with its targeting sequence and extensive direct human evidence. Reason: Mitochondrion is the established core compartment for AARS2 aminoacylation, editing, and hypoxia-responsive lactylation of mitochondrial substrates. Propagation Review Root cause: NO FAILURE CORE
GO:0006419 alanyl-tRNA aminoacylation	IEA GO_REF:0000120	MODIFY	Summary: Electronic assignment of the general alanyl-tRNA aminoacylation process; AARS2 performs this reaction specifically in mitochondria. Reason: The parent process is correct, but the mitochondrial child is both available and directly established for AARS2. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: mitochondrial alanyl-tRNA aminoacylation
GO:0008270 zinc ion binding	IEA GO_REF:0000104	ACCEPT	Summary: UniRule transfer of zinc-ion binding to the conserved AARS2 editing domain. Reason: Conserved zinc-coordinating residues form the editing active site, and human AARS2 mutagenesis/modeling links disruption of zinc coordination to loss of deacylation. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:29228266 This cysteine is fully conserved in AlaRSs, and is critical for zinc binding in the editing active site and thus for the deacylation reaction
GO:0043039 tRNA aminoacylation	IEA GO_REF:0000002	MODIFY	Summary: InterPro inference of broad tRNA aminoacylation from a conserved aminoacyl-tRNA synthetase domain. Reason: AARS2 has established alanine specificity and acts on mitochondrial tRNA(Ala), so the organelle- and substrate-specific child process is preferable. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Proposed replacements: mitochondrial alanyl-tRNA aminoacylation
GO:0106074 aminoacyl-tRNA metabolism involved in translational fidelity	IEA GO_REF:0000108	ACCEPT	Summary: Logical inference of aminoacyl-tRNA quality-control metabolism from AARS2's editing activity. Reason: The term accurately captures removal or prevention of incorrect amino acids on mitochondrial tRNA(Ala), a core translational-fidelity function directly demonstrated for human AARS2. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:29228266 These results indicate that tRNA proofreading is essential in mammalian mitochondria, and cannot be overcome by other quality control mechanisms.
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	MARK AS OVER ANNOTATED	Summary: The HuRI binary-interactome screen recovered AARS2 interactions with EHHADH and PTPA isoform 2, but generic protein binding conveys no molecular role. Reason: The screen interactions may be real, so removal is not warranted, but neither partner has a demonstrated consequence for AARS2 function in this source and GO:0005515 is intrinsically uninformative. No more specific molecular function should be inferred without mechanistic follow-up. Supporting Evidence: PMID:32296183 While HuRI displays highly significant overlap with known functional relationships, the cellular function of most individual PPIs remains to be elucidated.
GO:0141207 peptide lactyltransferase (ATP-dependent) activity	IEA GO_REF:0000120	ACCEPT	Summary: Electronic assignment of ATP-dependent peptide lactyltransferase activity from the exact Rhea reactions, corroborated by independent AARS2 studies of mitochondrial and cGAS substrates. Reason: AARS2 has a directly measured intrinsic ATP-dependent lactyltransferase activity. Treat it as a conditional secondary core function under elevated lactate or hypoxia and for specific substrates, not as the dominant source of basal global lysine lactylation. Propagation Review Root cause: NO FAILURE CORE Supporting Evidence: PMID:38163844 We show that mitochondrial alanyl-tRNA synthetase (AARS2) is a protein lysine lactyltransferase
GO:0160049 negative regulation of cGAS/STING signaling pathway	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: Electronic transfer of AARS2-dependent cGAS/STING inhibition, directly corroborated by the human AARS2 study under elevated-lactate conditions. Reason: Lactate-triggered AARS2 lactylation inactivates cGAS, so the sign and pathway term are correct. This is a condition-dependent downstream immune-regulatory outcome rather than the canonical mitochondrial translation function. The topology remains incompletely explained because mature AARS2 is mitochondrial, although a conditional cytosolic pool has been observed under hypoxia. Propagation Review Root cause: NO FAILURE NON CORE Supporting Evidence: PMID:39322678 In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS) and mediates its lactylation and inactivation in cells and in mice.
GO:0005739 mitochondrion	IDA GO_REF:0000052	ACCEPT	Summary: Curated immunofluorescence evidence places AARS2 in mitochondria. Reason: The localization agrees with the targeting sequence, disease study, high-confidence mitochondrial proteomics, and direct mitochondrial enzymology.
GO:0141207 peptide lactyltransferase (ATP-dependent) activity	IDA PMID:39322678 AARS1 and AARS2 sense L-lactate to regulate cGAS as global l...	ACCEPT	Summary: Direct ATP-dependent peptide lactyltransferase annotation with cGAS as the input and negative regulation of cGAS/STING signaling as the contextual process. Reason: The paper directly supports AARS2-catalyzed lactylation, and an independent full-text study measured ATP-dependent AARS2 lactylation of mitochondrial peptide substrates. Scope this intrinsic secondary activity to elevated-lactate, hypoxic, and substrate-specific settings; AARS2 is not required for basal global Kla in HEK293T cells. How mitochondrial AARS2 accesses cGAS remains unresolved. Supporting Evidence: PMID:39322678 they directly catalyse L-lactate for ATP-dependent lactylation on the lysine acceptor end PMID:38163844 Lactylation reactions were carried out in a 30 μL reaction mix containing 50 mM pH 7.5 HEPES, 25 mM KCl, 2 mM MgCl2, 1–10 mM lactate, 4 mM ATP, and 10 nM AARS2.
GO:0160049 negative regulation of cGAS/STING signaling pathway	IDA PMID:39322678 AARS1 and AARS2 sense L-lactate to regulate cGAS as global l...	KEEP AS NON CORE	Summary: Direct annotation of lactate-triggered cGAS inactivation by AARS2-mediated cGAS lactylation. Reason: The direction of regulation is correct and is supported in cells and mice, but this is a high-lactate downstream immune outcome rather than AARS2's canonical mitochondrial translation role. The study does not resolve how mature mitochondrial AARS2 accesses cytosolic or nuclear cGAS, so no constitutive extra-mitochondrial localization should be inferred. Supporting Evidence: PMID:39322678 In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS) and mediates its lactylation and inactivation in cells and in mice.
GO:0005739 mitochondrion	HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an...	ACCEPT	Summary: High-throughput quantitative proteomics places AARS2 in the high-confidence human mitochondrial proteome. Reason: This independent proteomic localization agrees with direct disease, enzymology, and subcellular-location evidence for AARS2's core mitochondrial residence. Supporting Evidence: PMID:34800366 We classified >8,000 proteins in mitochondrial preparations of human cells and defined a mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP).
GO:0004813 alanine-tRNA ligase activity	IMP PMID:21549344 Exome sequencing identifies mitochondrial alanyl-tRNA synthe...	ACCEPT	Summary: Experimental annotation from AARS2 cardiomyopathy variants that disrupt the catalytic aminoacylation function of mitochondrial AlaRS. Reason: The study supports the core alanine-tRNA ligase activity, and later recombinant human AARS2 and cybrid experiments confirm it directly. Because the cached source is abstract-only, retain the curator's full-text experimental assessment. Supporting Evidence: PMID:21549344 the second mutation severely disturbed the catalytic function, preventing tRNA aminoacylation
GO:0070143 mitochondrial alanyl-tRNA aminoacylation	IMP PMID:21549344 Exome sequencing identifies mitochondrial alanyl-tRNA synthe...	ACCEPT	Summary: Experimental annotation of mitochondrial alanyl-tRNA aminoacylation from AARS2 disease variants with impaired mitochondrial translation and respiratory-chain function. Reason: The term exactly captures AARS2's organelle-specific core process. Later human biochemical and cybrid evidence independently establishes mt-tRNA(Ala) charging; the cached original paper is abstract-only, so the curator's full-text assessment is retained. Supporting Evidence: PMID:21549344 the second mutation severely disturbed the catalytic function, preventing tRNA aminoacylation
GO:0005739 mitochondrion	IDA PMID:21549344 Exome sequencing identifies mitochondrial alanyl-tRNA synthe...	ACCEPT	Summary: Direct mitochondrial localization annotation from the study that identified AARS2 as the human mitochondrial alanyl-tRNA synthetase. Reason: Mitochondrial residence is independently corroborated by targeting-sequence, immunofluorescence, proteomic, enzymology, and mitochondrial-substrate evidence. The cache is abstract-only, so the curator's full-text IDA judgment is retained. Supporting Evidence: PMID:21549344 we showed to encode the mitochondrial alanyl-tRNA synthetase (mtAlaRS)
GO:0002196 Ser-tRNA(Ala) deacylase activity	IDA PMID:29228266 Editing activity for eliminating mischarged tRNAs is essenti...	NEW	Summary: Direct human biochemical annotation for hydrolysis of mischarged Ser-tRNA(Ala) by the AARS2 editing apparatus. Reason: Purified human mitochondrial AlaRS and editing-site variants were tested in a post-transfer deacylation assay with Ser-tRNA(Ala), directly establishing the substrate-specific activity represented by GO:0002196. Supporting Evidence: PMID:29228266 Determination of post-transfer editing of mischarged Ser-tRNAAla showed that the C749A mutant was severely defective in editing while the initial velocity of the post-transfer editing activity of the V760E mutant was only slightly reduced (Figure 1E and F).
GO:0106026 Gly-tRNA(Ala) deacylase activity	IDA PMID:30952159 The G3-U70-independent tRNA recognition by human mitochondri...	NEW	Summary: Direct human biochemical annotation for hydrolysis of mischarged Gly-tRNA(Ala) by the AARS2 editing apparatus. Reason: A post-transfer editing assay with human mitochondrial AlaRS showed loss of Gly-tRNA(Ala) hydrolysis by an editing-defective mutant, directly establishing the substrate-specific activity represented by GO:0106026. Live QuickGO, checked 2026-08-08, confirms that this is a current molecular-function term with the exact label used here. Supporting Evidence: PMID:30952159 Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla (Figure 5F).

Core Functions

In mitochondria, AARS2 activates L-alanine with ATP and transfers it to mitochondrial tRNA(Ala), producing Ala-tRNA(Ala) for mitochondrial translation. This organelle- specific aminoacylation reaction is the enzyme's primary conserved activity.

Molecular Function:

alanine-tRNA ligase activity

Directly Involved In:

mitochondrial alanyl-tRNA aminoacylation

Cellular Locations:

mitochondrion

Supporting Evidence:

PMID:32080176
Hs mt AlaRS charges cognate mt tRNAAla but not mt tRNAs specific for Asp, Leu, or Ser.
PMID:30262995
In this study, AARS2 overexpression did not result in a detectable increase of the mutated mt-tRNAAla but caused an increase incharged mt-tRNAAla in mutant cybrids, leading to enhanced mitochondrial translation. This strongly suggested that AARS2 improved the aminoacylation activity rather than preventing the degradation of mt-tRNAAla 5655A>G.

The embedded AARS2 editing apparatus proofreads mitochondrial tRNA(Ala) and hydrolyzes incorrectly attached serine and glycine. Direct human assays establish post-transfer Ser-tRNA(Ala) and Gly-tRNA(Ala) deacylation; glycine errors are also strongly cleared before transfer. Together these activities protect mitochondrial translational fidelity.

Molecular Function:

aminoacyl-tRNA deacylase activity

Directly Involved In:

aminoacyl-tRNA metabolism involved in translational fidelity

Cellular Locations:

mitochondrion

Supporting Evidence:

PMID:29228266
Determination of post-transfer editing of mischarged Ser-tRNAAla showed that the C749A mutant was severely defective in editing while the initial velocity of the post-transfer editing activity of the V760E mutant was only slightly reduced (Figure 1E and F).
PMID:30952159
Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla (Figure 5F).

As a conditional secondary activity under hypoxia or elevated intracellular lactate, AARS2 uses lactate and ATP to transfer lactyl groups to protein lysines. Directly demonstrated mitochondrial substrates include PDHA1 and CPT2. This is a context- and substrate-dependent activity rather than a basal global role: AARS2 depletion does not lower global lysine lactylation in untreated HEK293T cells. The reported cGAS signaling outcome is non-core because the route by which mitochondrial AARS2 encounters cytosolic or nuclear cGAS remains unresolved.

Molecular Function:

peptide lactyltransferase (ATP-dependent) activity

Cellular Locations:

mitochondrion

Supporting Evidence:

PMID:38163844
AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b) via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

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:0000104

Electronic Gene Ontology annotations created by transferring manual GO annotations between related proteins based on shared sequence features

GO_REF:0000108

Automatic assignment of GO terms using logical inference, based on on inter-ontology links

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:21549344

Exome sequencing identifies mitochondrial alanyl-tRNA synthetase mutations in infantile mitochondrial cardiomyopathy.

The foundational human genetics study identified AARS2 as encoding the mitochondrial alanyl-tRNA synthetase.

"Rigorous data analysis allowed us to identify a homozygous missense mutation in AARS2, which we showed to encode the mitochondrial alanyl-tRNA synthetase (mtAlaRS)."

PMID:32296183

A reference map of the human binary protein interactome.

PMID:34800366

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

PMID:29228266

Editing activity for eliminating mischarged tRNAs is essential in mammalian mitochondria.

Recombinant mature human AARS2 misactivates serine sufficiently to require proofreading.

"HmtAlaRS misactivated Ser with a discriminator factor of 1/569 (Table 1), which is significantly larger than 1/3300, the proposed threshold for frequency of errors in protein synthesis (31), suggesting that mtAlaRS requires editing function to prevent Ala-to-Ser misincorporation in mitochondria."
Human AARS2 directly performs post-transfer editing of Ser-tRNAAla; editing-domain substitutions impair this activity while largely preserving charging.

"In vitro aminoacylation assay indicated that the mutants C749A and V760E displayed only slightly decreased tRNAAla charging activity compared with wild type mtAlaRS (Figure 1D). Determination of post-transfer editing of mischarged Ser-tRNAAla showed that the C749A mutant was severely defective in editing while the initial velocity of the post-transfer editing activity of the V760E mutant was only slightly reduced (Figure 1E and F)."

PMID:30262995

Overexpression of human mitochondrial alanyl-tRNA synthetase suppresses biochemical defects of the mt-tRNA(Ala) mutation in cybrids.

AARS2 overexpression increases charging of mutant human mt-tRNAAla and improves mitochondrial translation.

"In this study, AARS2 overexpression did not result in a detectable increase of the mutated mt-tRNAAla but caused an increase incharged mt-tRNAAla in mutant cybrids, leading to enhanced mitochondrial translation. This strongly suggested that AARS2 improved the aminoacylation activity rather than preventing the degradation of mt-tRNAAla 5655A>G."

PMID:30285085

Instability of the mitochondrial alanyl-tRNA synthetase underlies fatal infantile-onset cardiomyopathy.

The cardiomyopathy-associated p.Arg580Trp variant primarily destabilizes AARS2 rather than abolishing its charging or editing chemistry.

"Taken together, our data suggest that the p.Arg580Trp variant impacts on stability of mt-AlaRS protein but not aminoacylation or editing activities and that the β-barrel subdomain has a critical role in protein folding and stability."

PMID:30952159

The G3-U70-independent tRNA recognition by human mitochondrial alanyl-tRNA synthetase.

Human mitochondrial AARS2 is monomeric and recognizes mt-tRNAAla without the canonical G3-U70 identity pair.

"In the present study, we found that hmtAlaRS is a monomer and recognizes mitochondrial tRNAAla in a G3-U70-independent manner, requiring several elements in the acceptor stem."
Human AARS2 misactivates glycine and has strong tRNA-independent pre-transfer editing against glycine.

"In addition, we found that hmtAlaRS misactivates noncognate Gly and catalyzes strong transfer RNA (tRNA)-independent pre-transfer editing for Gly."
Human AARS2 also performs post-transfer editing of Gly-tRNAAla.

"However, it synthesized more mischarged Gly-tRNAAla than did the wild-type hmtAlaRS, comparable with our previously constructed editing-defective C749A (42) (Figure 5D and E), supporting its defect in editing. Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla (Figure 5F)."

PMID:32080176

Relaxed sequence constraints favor mutational freedom in idiosyncratic metazoan mitochondrial tRNAs.

Purified human mitochondrial AARS2 selectively charges cognate mt-tRNAAla.

"Hs mt AlaRS charges cognate mt tRNAAla but not mt tRNAs specific for Asp, Leu, or Ser."
The AARS2 C-Ala domain helps fold and recognize the structurally flexible human mitochondrial tRNAAla elbow.

"The appended C-Ala domain, which plays an auxiliary role in prokaryotic AlaRSs and is dispensable for aminoacylation in the human cytoplasmic AlaRS system43,44, plays a central role as a folding aid for the intrinsically flexible mt tRNA elbow. Fine-tuned induced-fit adaptation selects mt tRNAAla and rejects non-cognate mt tRNAs (Supplementary Fig. 7g)."

PMID:38163844

Hypoxia induces mitochondrial protein lactylation to limit oxidative phosphorylation.

Recombinant AARS2 directly catalyzes ATP- and lactate-dependent lactylation of PDHA1 and CPT2 substrate peptides.

"AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b) via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms."
AARS2-dependent PDHA1 and CPT2 lactylation was observed under high-lactate conditions.

"Treatment with 10 mM Me-Lac increased the Lac-K336 and Lac-K457/8 levels of ectopically expressed PDHA1 (Fig. 5d) and CPT2 (Fig. 5e) in C2C12 and HL-1 cells (Supplementary information, Fig. S6g). However, the lactylation was not observed when Aars2 was knocked out (Fig. 5d, e)."

PMID:39322678

AARS1 and AARS2 sense L-lactate to regulate cGAS as global lysine lactyltransferases.

AARS1 and AARS2 bind L-lactate and directly catalyze ATP-dependent lysine lactylation.

"Here we identify the alanyl-tRNA synthetases AARS1 and AARS2 (AARS1/2) as intracellular L-lactate sensors required for L-lactate to stimulate the lysine lactylome in cells. AARS1/2 and the evolutionarily conserved Escherichia coli orthologue AlaRS bind to L-lactate with micromolar affinity and they directly catalyse L-lactate for ATP-dependent lactylation on the lysine acceptor end."
Under elevated L-lactate, AARS2 associates with and lactylates cGAS, inhibiting cGAS.

"In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS) and mediates its lactylation and inactivation in cells and in mice."

PMID:40835008

Class I histone deacetylases catalyze lysine lactylation.

AARS1 or AARS2 depletion does not reduce global basal lysine lactylation in the untreated proliferating HEK293T model.

"To compare the relative contribution of AARS enzymes towards global basal levels of Kla in cells, we used siRNA to knockdown AARS1 and AARS2. However, the knockdown of either enzyme did not alter Kla levels (Fig. S6, B–E), suggesting the AARS pathway is also not required for global lysine lactylation."

PMID:40301335

AARS2-catalyzed lactylation induces follicle development and premature ovarian insufficiency.

AARS2-dependent PDHA1/CPT2 lactylation occurs in a human granulosa-cell model, and the POI-associated R199C variant has increased activity.

"AARS2 deletion abrogated PDHA1 K336 and CPT2 K457/8 lactylation in the human granulosa cell line COV343 [38], and R199C exhibited a higher ability to lactylate PDHA1 K336 and CPT2 K457/8 in AARS2−/− COV343 cells (Fig. 3A, B)."

PMID:24808023

Novel (ovario) leukodystrophy related to AARS2 mutations.

Selected leukodystrophy-associated AARS2 variants were functionally assessed through a recombinant yeast model.

"The pathogenicity of the 2 AARS2 variants of P1 was proven in a recombinant yeast model."

PMID:42010330

PCBP1 regulates alternative splicing of AARS2 in congenital cardiomyopathy.

PCBP1-binding motifs and human PCBP1 are required for inclusion of AARS2 exon 16 in human cell-based minigene assays.

"We found that mutations of either PCBP1 site 1 or site 2, or canonical splice donor or acceptor sites, are sufficient to cause exclusion of AARS2 exon-16 (Fig. 1l,m). Knockdown of human PCBP1 in both systems shows a similar pattern of AARS2 exon-16 exclusion (Fig. 1l,m and Extended Data Fig. 1c)."

Reactome:R-HSA-380177

alanine + tRNA(Ala) + ATP => Ala-tRNA(Ala) + AMP + pyrophosphate

Reactome represents AARS2-catalyzed mitochondrial alanine-tRNA charging.

"AARS2 (mitochondrial alanyl tRNA synthetase) catalyzes the reaction of alanine, mitochondrial tRNA(Ala), and ATP to form Ala-tRNA(Ala), AMP, and pyrophosphate."

file:human/AARS2/AARS2-uniprot.txt

UniProtKB/Swiss-Prot record for human AARS2 (Q5JTZ9)

UniProt records alanine charging and editing of incorrectly charged tRNAAla as AARS2's canonical functions.

"CC -!- FUNCTION: Catalyzes the attachment of alanine to tRNA(Ala) in a two- CC step reaction: alanine is first activated by ATP to form Ala-AMP and CC then transferred to the acceptor end of tRNA(Ala). Also edits CC incorrectly charged tRNA(Ala) via its editing domain (PubMed:21549344)."
UniProt locates the reviewed AARS2 product in mitochondria.

"CC -!- SUBCELLULAR LOCATION: Mitochondrion {ECO:0000255|HAMAP-Rule:MF_03133, CC ECO:0000269|PubMed:21549344}."
UniProt flags the unresolved compartmental access underlying AARS2-mediated cGAS lactylation.

"CC -!- CAUTION: Given that AARS2 is a mitochondrial protein, it is unclear how CC it can mediate lactylation of CGAS, which localizes in the cytosol and CC nucleus. {ECO:0000269|PubMed:39322678}."

Suggested Experiments

Experiment: Introduce matched separation-of-function AARS2 variants into an acute AARS2-depletion background, then quantify charging and mischarging of mitochondrial tRNA(Ala) and Ala-to-Gly or Ala-to-Ser substitutions in pulse-labeled mitochondrial translation products. Complement the cell measurements with pre-transfer and single-turnover post-transfer kinetics using purified human AARS2.

Hypothesis: AARS2 uses mechanistically distinct proofreading routes for glycine and serine errors that make different contributions to mitochondrial translational fidelity in human cells.

Type: mitochondrial tRNA biochemistry and quantitative mitoproteomics

Experiment: Use acute endogenous AARS2 degradation across calibrated intracellular lactate and oxygen ranges, followed by isotope-resolved quantitative lactyl-proteomics and targeted measurement of PDHA1 K336 and CPT2 K457/K458. Rescue with matched-expression AARS2 variants that retain alanine charging but differ in lactyltransferase activity, and compare with class I HDAC perturbation.

Hypothesis: Endogenous AARS2 contributes substantially to a restricted, high-lactate mitochondrial lactylome but not to basal global lysine lactylation.

Type: acute perturbation and quantitative lactyl-proteomics

Experiment: Endogenously tag both termini of AARS2, distinguish precursor from mature protein, and combine quantitative fractionation, protease protection, live-cell imaging, and cGAS-directed proximity labeling before and after lactate exposure. Perturb the mitochondrial targeting sequence and import machinery while measuring site-specific cGAS lactylation and cGAS-STING signaling, with charging-competent rescue controls.

Hypothesis: A lactate-responsive AARS2 precursor or inducible extramitochondrial species directly encounters cGAS, whereas the mature mitochondrial pool does not.

Type: compartment-resolved trafficking and proximity analysis

Knowledge Gaps

What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).

Gap: The relative in vivo contributions of AARS2 pre-transfer and post-transfer editing to clearance of glycine errors, and the physiological balance between glycine and serine mischarging of mitochondrial tRNA(Ala), remain unresolved in human cells.

OPEN BIOLOGY RESIDUAL_SUBGAP

What is known: Purified human AARS2 directly edits both Gly-tRNA(Ala) and Ser-tRNA(Ala), with biochemical evidence for strong glycine pre-transfer editing and post-transfer hydrolysis of both mischarged products. These assays establish the activities but do not quantify their separate contributions under endogenous mitochondrial substrate concentrations.

Significance: Resolving the editing pathway used for each error would clarify which proofreading defect drives mitochondrial mistranslation in different AARS2 alleles and metabolic states.

What would resolve it: Use separation-of-function AARS2 variants in human cells and directly quantify aminoacylated and mischarged mitochondrial tRNA(Ala), together with Ala-to-Ser and Ala-to-Gly substitutions in newly synthesized mitochondrial proteins.

Provenance (the field's own admissions):

"Determination of post-transfer editing of mischarged Ser-tRNAAla showed that the C749A mutant was severely defective in editing while the initial velocity of the post-transfer editing activity of the V760E mutant was only slightly reduced (Figure 1E and F)." — PMID:29228266
"Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla (Figure 5F)." — PMID:30952159

Gap: The physiological lactate range, cell states, tissues, and substrate spectrum in which endogenous AARS2 materially contributes to protein lysine lactylation, relative to class I HDACs and other routes, remain incompletely defined.

OPEN BIOLOGYCURATION RESIDUAL_SUBGAP

What is known: AARS2-dependent lactylation of PDHA1 and CPT2 is supported under exercise-, hypoxia-, or lactate-associated conditions, whereas AARS2 knockdown does not reduce basal global lysine lactylation in untreated HEK293T cells.

Significance: A quantitative boundary is needed to distinguish physiological AARS2 substrates from high-lactate or overexpression effects and to avoid generalizing a conditional, target-specific activity to the basal lactylome.

What would resolve it: Quantify endogenous site-resolved lactylation across calibrated intracellular lactate and oxygen ranges after acute AARS2 depletion and matched rescue, alongside class I HDAC perturbation and measurements of mitochondrial alanine charging.

Provenance (the field's own admissions):

"AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b) via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms." — PMID:38163844
"However, the knockdown of either enzyme did not alter Kla levels (Fig. S6, B–E), suggesting the AARS pathway is also not required for global lysine lactylation." — PMID:40835008

Gap: How a mitochondrial AARS2 pool accesses cytosolic or nuclear cGAS for the reported lactate-responsive modification is unknown, and no stable extramitochondrial AARS2 pool or trafficking mechanism has been established.

OPEN BIOLOGYCURATION RESIDUAL_SUBGAP

What is known: Reviewed localization evidence places AARS2 in mitochondria, while a cGAS study reports AARS2-dependent cGAS lactylation. The compartmental mismatch is explicitly unresolved and does not justify assigning a routine cytosolic or nuclear location.

Significance: Defining the relevant AARS2 species and compartment is necessary to distinguish a direct signaling mechanism from indirect metabolic effects and to curate cellular locations without over-annotation.

What would resolve it: Endogenously tag AARS2 and resolve its precursor and mature forms by quantitative fractionation, protease protection, and live-cell imaging during lactate exposure; combine this with AARS2-cGAS proximity labeling and mitochondrial-import perturbation.

Provenance (the field's own admissions):

"CC -!- CAUTION: Given that AARS2 is a mitochondrial protein, it is unclear how CC it can mediate lactylation of CGAS, which localizes in the cytosol and CC nucleus. {ECO:0000269|PubMed:39322678}." — file:human/AARS2/AARS2-uniprot.txt

📚 Additional Documentation

Notes

(AARS2-notes.md)

AARS2 review notes

Research provenance

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Live QuickGO returned 26 rows but 25 normalized review tuples. Two PMID:32296183 protein-binding rows collapse into one tuple, so both partners must remain in supporting_entities. The PMID:39322678 lactyltransferase row also carries has_input CGAS and part_of negative regulation of cGAS/STING signaling; the local 16-column GOA export does not encode that extension, so it was restored from the live record.

Functional evidence map

The canonical function is mitochondrial alanine charging. Purified human AARS2 is selective for its cognate mitochondrial alanine tRNA [PMID:32080176, "Hs mt AlaRS charges cognate mt tRNAAla but not mt tRNAs specific for Asp, Leu, or Ser."]. Human cybrid rescue independently increases charged mutant mt-tRNA(Ala) and mitochondrial translation [PMID:30262995, "AARS2 overexpression did not result in a detectable increase of the mutated mt-tRNAAla but caused an increase incharged mt-tRNAAla in mutant cybrids, leading to enhanced mitochondrial translation."].
Proofreading is a second canonical activity. Recombinant mature human AARS2 directly performs post-transfer Ser-tRNA(Ala) editing [PMID:29228266, "Determination of post-transfer editing of mischarged Ser-tRNAAla showed that the C749A mutant was severely defective in editing while the initial velocity of the post-transfer editing activity of the V760E mutant was only slightly reduced"]. Human AARS2 also performs Gly-tRNA(Ala) editing; an editing-site mutant loses that hydrolysis [PMID:30952159, "Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E was unable to hydrolyze Gly-tRNAAla"]. These support direct IDA recommendations for the Ser- and Gly-specific child terms in addition to the true broad deacylase parent.
The mature enzyme is monomeric, so no stable complex belongs in the core synthesis [PMID:30952159, "In the present study, we found that hmtAlaRS is a monomer"].
ATP-dependent protein lactylation is experimentally supported but conditional. AARS2 lactylates PDHA1/CPT2 peptides in an ATP- and lactate-dependent reaction [PMID:38163844, "AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b) via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms."]. The cGAS work reports lactate-induced association, lactylation and inactivation [PMID:39322678, "In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS) and mediates its lactylation and inactivation in cells and in mice."]. However, AARS2 depletion does not reduce basal global lysine lactylation in untreated HEK293T cells [PMID:40835008, "However, the knockdown of either enzyme did not alter Kla levels (Fig. S6, B–E), suggesting the AARS pathway is also not required for global lysine lactylation."].
The cGAS mechanism has an unresolved localization problem rather than evidence for a routine cytosolic AARS2 pool [file:human/AARS2/AARS2-uniprot.txt, "Given that AARS2 is a mitochondrial protein, it is unclear how it can mediate lactylation of CGAS, which localizes in the cytosol and nucleus."].
Disease mechanisms are allele-specific. For example, p.Arg580Trp mainly destabilizes the protein rather than abolishing catalytic chemistry [PMID:30285085, "Taken together, our data suggest that the p.Arg580Trp variant impacts on stability of mt-AlaRS protein but not aminoacylation or editing activities"]. Disease phenotypes therefore should not be promoted to core molecular functions.

Curation priorities

Replace broad nucleotide, nucleic-acid, aminoacyl-tRNA-ligase and tRNA-aminoacylation terms with ATP binding, tRNA binding, alanine-tRNA ligase activity and mitochondrial alanyl-tRNA aminoacylation, respectively.
Treat the InterPro-derived cytoplasm row as an overly broad localization mapping and prefer mitochondrion; do not use the cGAS report to infer a normal cytosolic or nuclear isoform.
Mark the merged HuRI protein-binding tuple as over-annotated: the two binary partners are retained for provenance, but neither defines a stable complex or core function.
Keep the lactyltransferase activity as a genuine conditional secondary activity and the cGAS/STING process as non-core/contextual.
Add direct human IDA recommendations for GO:0002196 Ser-tRNA(Ala) deacylase activity and GO:0106026 Gly-tRNA(Ala) deacylase activity.

📄 View Raw YAML

id: Q5JTZ9
gene_symbol: AARS2
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  AARS2 is a nuclear-encoded, monomeric class II alanyl-tRNA synthetase that is
  imported into mitochondria. It activates L-alanine with ATP and transfers alanine
  to mitochondrial tRNA(Ala), supplying Ala-tRNA(Ala) for mitochondrial translation.
  Its editing apparatus hydrolyzes mischarged Ser-tRNA(Ala) and Gly-tRNA(Ala), thereby
  preserving mitochondrial translational fidelity, while its C-Ala domain contributes
  to recognition of the structurally idiosyncratic mitochondrial tRNA(Ala). Under
  hypoxia or elevated intracellular lactate, AARS2 can additionally use ATP and lactate
  to lactylate protein lysines on mitochondrial substrates such as PDHA1 and CPT2.
  Lactate-responsive cGAS lactylation has also been reported, although how mitochondrial
  AARS2 accesses cytosolic or nuclear cGAS remains unresolved. Pathogenic biallelic
  variants can impair AARS2 abundance or alanine charging and cause tissue-selective
  mitochondrial disease, including infantile cardiomyopathy and leukodystrophy with
  ovarian failure.
existing_annotations:
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  supporting_entities:
  - PANTHER:PTN002622939
  - UniProtKB:Q5JTZ9
  review:
    summary: >-
      IBA assignment of AARS2 activity in mitochondria, independently supported by
      mitochondrial import, enzymology, proteomics, and hypoxia-response studies.
    action: ACCEPT
    reason: >-
      Mitochondria are the established execution site for AARS2's canonical tRNA
      aminoacylation and editing functions and for its hypoxia-responsive lactylation
      of mitochondrial substrates.
    additional_reference_ids:
    - PMID:21549344
    - PMID:29228266
    - PMID:38163844
    propagation_review:
      root_cause: NO_FAILURE_CORE
- term:
    id: GO:0070143
    label: mitochondrial alanyl-tRNA aminoacylation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  supporting_entities:
  - PANTHER:PTN002622939
  - UniProtKB:Q5JTZ9
  review:
    summary: >-
      IBA assignment of the mitochondrial alanine-charging process, corroborated by
      direct recombinant-enzyme assays and rescue of defective mt-tRNA(Ala) charging
      in human cybrids.
    action: ACCEPT
    reason: >-
      This is the organelle-specific core process executed by AARS2 and is at the
      appropriate GO granularity.
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:30262995
      supporting_text: >-
        This indicated that AARS2 improved the aminoacylation activity in the case of
        m.5655A>G, rather than having a stabilizing effect on the tRNA structure.
- term:
    id: GO:0004813
    label: alanine-tRNA ligase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  supporting_entities:
  - CGD:CAL0000182169
  - MGI:MGI:2384560
  - PANTHER:PTN000206950
  - RGD:1304832
  - SGD:S000005862
  - UniProtKB:P00957
  - UniProtKB:P49588
  - UniProtKB:Q5JTZ9
  review:
    summary: >-
      IBA assignment of substrate-specific alanine-tRNA ligase activity, directly
      confirmed for purified human mitochondrial AlaRS and in human-cell tRNA-charging
      rescue experiments.
    action: ACCEPT
    reason: >-
      Alanine-tRNA ligase activity is AARS2's principal conserved molecular function.
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:30262995
      supporting_text: >-
        This indicated that AARS2 improved the aminoacylation activity in the case of
        m.5655A>G, rather than having a stabilizing effect on the tRNA structure.
- term:
    id: GO:0002161
    label: aminoacyl-tRNA deacylase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  supporting_entities:
  - MGI:MGI:2384560
  - PANTHER:PTN000206950
  - UniProtKB:P00957
  - UniProtKB:P49588
  - UniProtKB:Q57984
  review:
    summary: >-
      IBA assignment of the broad aminoacyl-tRNA deacylase activity, supported by
      direct human AARS2 proofreading studies of mischarged Ser-tRNA(Ala) and
      Gly-tRNA(Ala).
    action: ACCEPT
    reason: >-
      This IBA source term is a true broad proofreading activity independently
      corroborated by direct human assays of both Ser-tRNA(Ala) and Gly-tRNA(Ala).
      Retaining the parent accurately represents the family-level inference, while
      the appended substrate-specific NEW rows separately capture the direct evidence.
    additional_reference_ids:
    - PMID:29228266
    - PMID:30952159
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:29228266
      supporting_text: >-
        We demonstrate here that the human mitochondrial AlaRS is capable of editing
        mischarged tRNAs in vitro
    - reference_id: PMID:30952159
      supporting_text: >-
        Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E
        was unable to hydrolyze Gly-tRNAAla (Figure 5F).
- term:
    id: GO:0000166
    label: nucleotide binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  supporting_entities:
  - InterPro:IPR002318
  - InterPro:IPR018162
  - InterPro:IPR018163
  - InterPro:IPR018164
  review:
    summary: >-
      InterPro inference of generic nucleotide binding from conserved AlaRS domains;
      the physiologically relevant nucleotide substrate is ATP.
    action: MODIFY
    reason: >-
      Nucleotide binding is true but too broad. Human AARS2 uses ATP for alanine
      activation and for its conditional lactyltransferase reaction, so ATP binding
      is the informative replacement.
    proposed_replacement_terms:
    - id: GO:0005524
      label: ATP binding
    additional_reference_ids:
    - PMID:30952159
    - PMID:39322678
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0003676
    label: nucleic acid binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  supporting_entities:
  - InterPro:IPR018165
  review:
    summary: >-
      InterPro inference of generic nucleic-acid binding; AARS2's established
      physiological nucleic-acid ligand is mitochondrial tRNA(Ala).
    action: MODIFY
    reason: >-
      Replace the uninformative parent with tRNA binding, which is directly supported
      by biochemical dissection of human mitochondrial AlaRS recognition of
      mt-tRNA(Ala).
    proposed_replacement_terms:
    - id: GO:0000049
      label: tRNA binding
    additional_reference_ids:
    - PMID:30952159
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0004812
    label: aminoacyl-tRNA ligase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  supporting_entities:
  - InterPro:IPR012947
  review:
    summary: >-
      InterPro inference of broad aminoacyl-tRNA ligase activity from an aaRS
      additional domain.
    action: MODIFY
    reason: >-
      The activity class is correct, but alanine specificity is firmly established
      for AARS2 and should be stated explicitly.
    proposed_replacement_terms:
    - id: GO:0004813
      label: alanine-tRNA ligase activity
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0004813
    label: alanine-tRNA ligase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  supporting_entities:
  - InterPro:IPR018162
  - InterPro:IPR018164
  - InterPro:IPR018165
  - InterPro:IPR023033
  - RHEA:12540
  - EC:6.1.1.7
  - UniRule:UR000375824
  review:
    summary: >-
      Convergent ARBA, UniRule, InterPro, EC 6.1.1.7, and RHEA:12540 assignment
      of alanine-tRNA ligase activity.
    action: ACCEPT
    reason: >-
      The electronic mapping exactly matches the directly characterized core reaction
      of human mitochondrial AlaRS.
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: NO_FAILURE_CORE
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  supporting_entities:
  - InterPro:IPR012947
  - InterPro:IPR018162
  - InterPro:IPR018164
  - InterPro:IPR018165
  - UniRule:UR000375824
  review:
    summary: >-
      Electronic ATP-binding assignment from conserved AlaRS catalytic domains and
      UniRule.
    action: ACCEPT
    reason: >-
      ATP is required to form the aminoacyl-adenylate intermediate in alanine charging
      and is also required by the conditional lactyltransferase reaction.
    additional_reference_ids:
    - PMID:30952159
    - PMID:38163844
    - PMID:39322678
    propagation_review:
      root_cause: NO_FAILURE_CORE
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: located_in
  supporting_entities:
  - InterPro:IPR002318
  - InterPro:IPR018162
  review:
    summary: >-
      InterPro assigns the broad cellular-component term cytoplasm from AlaRS domains.
      Because GO cytoplasm includes organelles, the row is not false, but it is
      needlessly broad for this mitochondrial enzyme.
    action: MODIFY
    reason: >-
      Replace this parent location with mitochondrion, the established core location
      of mature AARS2. Hypoxia studies detected a contextual cytosolic pool, but this
      IEA carries no such condition and should not be taken as evidence for constitutive
      cytosolic availability. The route by which mitochondrial AARS2 reaches cGAS in
      the lactate-response study remains unresolved.
    proposed_replacement_terms:
    - id: GO:0005739
      label: mitochondrion
    additional_reference_ids:
    - PMID:21549344
    - PMID:29228266
    - PMID:34800366
    - PMID:38163844
    - PMID:39322678
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  supporting_entities:
  - UniProtKB-SubCell:SL-0173
  review:
    summary: >-
      UniProt subcellular-location mapping places AARS2 in mitochondria, consistent
      with its targeting sequence and extensive direct human evidence.
    action: ACCEPT
    reason: >-
      Mitochondrion is the established core compartment for AARS2 aminoacylation,
      editing, and hypoxia-responsive lactylation of mitochondrial substrates.
    additional_reference_ids:
    - PMID:21549344
    - PMID:29228266
    - PMID:34800366
    - PMID:38163844
    propagation_review:
      root_cause: NO_FAILURE_CORE
- term:
    id: GO:0006419
    label: alanyl-tRNA aminoacylation
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  supporting_entities:
  - ARBA:ARBA00085735
  - InterPro:IPR018162
  - InterPro:IPR018164
  - InterPro:IPR018165
  review:
    summary: >-
      Electronic assignment of the general alanyl-tRNA aminoacylation process;
      AARS2 performs this reaction specifically in mitochondria.
    action: MODIFY
    reason: >-
      The parent process is correct, but the mitochondrial child is both available
      and directly established for AARS2.
    proposed_replacement_terms:
    - id: GO:0070143
      label: mitochondrial alanyl-tRNA aminoacylation
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0008270
    label: zinc ion binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000104
  qualifier: enables
  supporting_entities:
  - UniRule:UR000375824
  review:
    summary: >-
      UniRule transfer of zinc-ion binding to the conserved AARS2 editing domain.
    action: ACCEPT
    reason: >-
      Conserved zinc-coordinating residues form the editing active site, and human
      AARS2 mutagenesis/modeling links disruption of zinc coordination to loss of
      deacylation.
    additional_reference_ids:
    - PMID:29228266
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:29228266
      supporting_text: >-
        This cysteine is fully conserved in AlaRSs, and is critical for zinc binding
        in the editing active site and thus for the deacylation reaction
- term:
    id: GO:0043039
    label: tRNA aminoacylation
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  supporting_entities:
  - InterPro:IPR012947
  review:
    summary: >-
      InterPro inference of broad tRNA aminoacylation from a conserved aminoacyl-tRNA
      synthetase domain.
    action: MODIFY
    reason: >-
      AARS2 has established alanine specificity and acts on mitochondrial tRNA(Ala),
      so the organelle- and substrate-specific child process is preferable.
    proposed_replacement_terms:
    - id: GO:0070143
      label: mitochondrial alanyl-tRNA aminoacylation
    additional_reference_ids:
    - PMID:30262995
    - PMID:30952159
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
- term:
    id: GO:0106074
    label: aminoacyl-tRNA metabolism involved in translational fidelity
  evidence_type: IEA
  original_reference_id: GO_REF:0000108
  qualifier: involved_in
  supporting_entities:
  - GO:0002161
  review:
    summary: >-
      Logical inference of aminoacyl-tRNA quality-control metabolism from AARS2's
      editing activity.
    action: ACCEPT
    reason: >-
      The term accurately captures removal or prevention of incorrect amino acids on
      mitochondrial tRNA(Ala), a core translational-fidelity function directly
      demonstrated for human AARS2.
    additional_reference_ids:
    - PMID:29228266
    - PMID:30952159
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:29228266
      supporting_text: >-
        These results indicate that tRNA proofreading is essential in mammalian
        mitochondria, and cannot be overcome by other quality control mechanisms.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  supporting_entities:
  - UniProtKB:Q08426
  - UniProtKB:Q15257-2
  review:
    summary: >-
      The HuRI binary-interactome screen recovered AARS2 interactions with EHHADH and
      PTPA isoform 2, but generic protein binding conveys no molecular role.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The screen interactions may be real, so removal is not warranted, but neither
      partner has a demonstrated consequence for AARS2 function in this source and
      GO:0005515 is intrinsically uninformative. No more specific molecular function
      should be inferred without mechanistic follow-up.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: >-
        While HuRI displays highly significant overlap with known functional
        relationships, the cellular function of most individual PPIs remains to be
        elucidated.
- term:
    id: GO:0141207
    label: peptide lactyltransferase (ATP-dependent) activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  supporting_entities:
  - ARBA:ARBA00085408
  - UniProtKB:Q14CH7
  - ensembl:ENSMUSP00000024733
  - RHEA:80271
  - RHEA:80275
  review:
    summary: >-
      Electronic assignment of ATP-dependent peptide lactyltransferase activity from
      the exact Rhea reactions, corroborated by independent AARS2 studies of
      mitochondrial and cGAS substrates.
    action: ACCEPT
    reason: >-
      AARS2 has a directly measured intrinsic ATP-dependent lactyltransferase activity.
      Treat it as a conditional secondary core function under elevated lactate or
      hypoxia and for specific substrates, not as the dominant source of basal global
      lysine lactylation.
    additional_reference_ids:
    - PMID:38163844
    - PMID:39322678
    - PMID:40835008
    propagation_review:
      root_cause: NO_FAILURE_CORE
    supported_by:
    - reference_id: PMID:38163844
      supporting_text: >-
        We show that mitochondrial alanyl-tRNA synthetase (AARS2) is a protein lysine
        lactyltransferase
- term:
    id: GO:0160049
    label: negative regulation of cGAS/STING signaling pathway
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  supporting_entities:
  - ARBA:ARBA00088339
  - UniProtKB:Q14CH7
  - ensembl:ENSMUSP00000024733
  review:
    summary: >-
      Electronic transfer of AARS2-dependent cGAS/STING inhibition, directly
      corroborated by the human AARS2 study under elevated-lactate conditions.
    action: KEEP_AS_NON_CORE
    reason: >-
      Lactate-triggered AARS2 lactylation inactivates cGAS, so the sign and pathway
      term are correct. This is a condition-dependent downstream immune-regulatory
      outcome rather than the canonical mitochondrial translation function. The
      topology remains incompletely explained because mature AARS2 is mitochondrial,
      although a conditional cytosolic pool has been observed under hypoxia.
    additional_reference_ids:
    - PMID:38163844
    - PMID:39322678
    - PMID:40835008
    propagation_review:
      root_cause: NO_FAILURE_NON_CORE
    supported_by:
    - reference_id: PMID:39322678
      supporting_text: >-
        In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS)
        and mediates its lactylation and inactivation in cells and in mice.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      Curated immunofluorescence evidence places AARS2 in mitochondria.
    action: ACCEPT
    reason: >-
      The localization agrees with the targeting sequence, disease study,
      high-confidence mitochondrial proteomics, and direct mitochondrial enzymology.
    additional_reference_ids:
    - PMID:21549344
    - PMID:29228266
    - PMID:34800366
    - PMID:38163844
- term:
    id: GO:0141207
    label: peptide lactyltransferase (ATP-dependent) activity
  evidence_type: IDA
  original_reference_id: PMID:39322678
  qualifier: enables
  extensions:
  - predicate: RO:0002233
    term:
      id: UniProtKB:Q8N884
      label: CGAS
  - predicate: BFO:0000050
    term:
      id: GO:0160049
      label: negative regulation of cGAS/STING signaling pathway
  review:
    summary: >-
      Direct ATP-dependent peptide lactyltransferase annotation with cGAS as the input
      and negative regulation of cGAS/STING signaling as the contextual process.
    action: ACCEPT
    reason: >-
      The paper directly supports AARS2-catalyzed lactylation, and an independent
      full-text study measured ATP-dependent AARS2 lactylation of mitochondrial
      peptide substrates. Scope this intrinsic secondary activity to elevated-lactate,
      hypoxic, and substrate-specific settings; AARS2 is not required for basal global
      Kla in HEK293T cells. How mitochondrial AARS2 accesses cGAS remains unresolved.
    additional_reference_ids:
    - PMID:38163844
    - PMID:40835008
    supported_by:
    - reference_id: PMID:39322678
      supporting_text: >-
        they directly catalyse L-lactate for ATP-dependent lactylation on the lysine
        acceptor end
    - reference_id: PMID:38163844
      supporting_text: >-
        Lactylation reactions were carried out in a 30 μL reaction mix containing
        50 mM pH 7.5 HEPES, 25 mM KCl, 2 mM MgCl2, 1–10 mM lactate, 4 mM ATP,
        and 10 nM AARS2.
- term:
    id: GO:0160049
    label: negative regulation of cGAS/STING signaling pathway
  evidence_type: IDA
  original_reference_id: PMID:39322678
  qualifier: involved_in
  review:
    summary: >-
      Direct annotation of lactate-triggered cGAS inactivation by AARS2-mediated
      cGAS lactylation.
    action: KEEP_AS_NON_CORE
    reason: >-
      The direction of regulation is correct and is supported in cells and mice, but
      this is a high-lactate downstream immune outcome rather than AARS2's canonical
      mitochondrial translation role. The study does not resolve how mature
      mitochondrial AARS2 accesses cytosolic or nuclear cGAS, so no constitutive
      extra-mitochondrial localization should be inferred.
    additional_reference_ids:
    - PMID:38163844
    - PMID:40835008
    supported_by:
    - reference_id: PMID:39322678
      supporting_text: >-
        In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS)
        and mediates its lactylation and inactivation in cells and in mice.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: HTP
  original_reference_id: PMID:34800366
  qualifier: located_in
  review:
    summary: >-
      High-throughput quantitative proteomics places AARS2 in the high-confidence
      human mitochondrial proteome.
    action: ACCEPT
    reason: >-
      This independent proteomic localization agrees with direct disease, enzymology,
      and subcellular-location evidence for AARS2's core mitochondrial residence.
    additional_reference_ids:
    - PMID:21549344
    - PMID:29228266
    - PMID:38163844
    supported_by:
    - reference_id: PMID:34800366
      supporting_text: >-
        We classified >8,000 proteins in mitochondrial preparations of human cells
        and defined a mitochondrial high-confidence proteome of >1,100 proteins
        (MitoCoP).
- term:
    id: GO:0004813
    label: alanine-tRNA ligase activity
  evidence_type: IMP
  original_reference_id: PMID:21549344
  qualifier: enables
  review:
    summary: >-
      Experimental annotation from AARS2 cardiomyopathy variants that disrupt the
      catalytic aminoacylation function of mitochondrial AlaRS.
    action: ACCEPT
    reason: >-
      The study supports the core alanine-tRNA ligase activity, and later recombinant
      human AARS2 and cybrid experiments confirm it directly. Because the cached
      source is abstract-only, retain the curator's full-text experimental assessment.
    additional_reference_ids:
    - PMID:29228266
    - PMID:30262995
    - PMID:30952159
    supported_by:
    - reference_id: PMID:21549344
      supporting_text: >-
        the second mutation severely disturbed the catalytic function, preventing
        tRNA aminoacylation
- term:
    id: GO:0070143
    label: mitochondrial alanyl-tRNA aminoacylation
  evidence_type: IMP
  original_reference_id: PMID:21549344
  qualifier: involved_in
  review:
    summary: >-
      Experimental annotation of mitochondrial alanyl-tRNA aminoacylation from AARS2
      disease variants with impaired mitochondrial translation and respiratory-chain
      function.
    action: ACCEPT
    reason: >-
      The term exactly captures AARS2's organelle-specific core process. Later human
      biochemical and cybrid evidence independently establishes mt-tRNA(Ala) charging;
      the cached original paper is abstract-only, so the curator's full-text assessment
      is retained.
    additional_reference_ids:
    - PMID:29228266
    - PMID:30262995
    - PMID:30952159
    supported_by:
    - reference_id: PMID:21549344
      supporting_text: >-
        the second mutation severely disturbed the catalytic function, preventing
        tRNA aminoacylation
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: PMID:21549344
  qualifier: located_in
  review:
    summary: >-
      Direct mitochondrial localization annotation from the study that identified
      AARS2 as the human mitochondrial alanyl-tRNA synthetase.
    action: ACCEPT
    reason: >-
      Mitochondrial residence is independently corroborated by targeting-sequence,
      immunofluorescence, proteomic, enzymology, and mitochondrial-substrate evidence.
      The cache is abstract-only, so the curator's full-text IDA judgment is retained.
    additional_reference_ids:
    - PMID:29228266
    - PMID:34800366
    - PMID:38163844
    supported_by:
    - reference_id: PMID:21549344
      supporting_text: >-
        we showed to encode the mitochondrial alanyl-tRNA synthetase (mtAlaRS)
- term:
    id: GO:0002196
    label: Ser-tRNA(Ala) deacylase activity
  evidence_type: IDA
  original_reference_id: PMID:29228266
  qualifier: enables
  review:
    summary: >-
      Direct human biochemical annotation for hydrolysis of mischarged
      Ser-tRNA(Ala) by the AARS2 editing apparatus.
    action: NEW
    reason: >-
      Purified human mitochondrial AlaRS and editing-site variants were tested in a
      post-transfer deacylation assay with Ser-tRNA(Ala), directly establishing the
      substrate-specific activity represented by GO:0002196.
    supported_by:
    - reference_id: PMID:29228266
      supporting_text: >-
        Determination of post-transfer editing of mischarged Ser-tRNAAla showed that
        the C749A mutant was severely defective in editing while the initial velocity
        of the post-transfer editing activity of the V760E mutant was only slightly
        reduced (Figure 1E and F).
- term:
    id: GO:0106026
    label: Gly-tRNA(Ala) deacylase activity
  evidence_type: IDA
  original_reference_id: PMID:30952159
  qualifier: enables
  review:
    summary: >-
      Direct human biochemical annotation for hydrolysis of mischarged
      Gly-tRNA(Ala) by the AARS2 editing apparatus.
    action: NEW
    reason: >-
      A post-transfer editing assay with human mitochondrial AlaRS showed loss of
      Gly-tRNA(Ala) hydrolysis by an editing-defective mutant, directly establishing
      the substrate-specific activity represented by GO:0106026. Live QuickGO,
      checked 2026-08-08, confirms that this is a current molecular-function term
      with the exact label used here.
    supported_by:
    - reference_id: PMID:30952159
      supporting_text: >-
        Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E
        was unable to hydrolyze Gly-tRNAAla (Figure 5F).
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- 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:0000104
  title: Electronic Gene Ontology annotations created by transferring manual GO annotations
    between related proteins based on shared sequence features
  findings: []
- id: GO_REF:0000108
  title: Automatic assignment of GO terms using logical inference, based on on inter-ontology
    links
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:21549344
  title: Exome sequencing identifies mitochondrial alanyl-tRNA synthetase mutations
    in infantile mitochondrial cardiomyopathy.
  full_text_unavailable: true
  findings:
  - statement: >-
      The foundational human genetics study identified AARS2 as encoding the
      mitochondrial alanyl-tRNA synthetase.
    supporting_text: >-
      Rigorous data analysis allowed us to identify a homozygous missense mutation
      in AARS2, which we showed to encode the mitochondrial alanyl-tRNA synthetase
      (mtAlaRS).
    reference_section_type: ABSTRACT
    full_text_unavailable: true
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Foundational human disease and mitochondrial-identity paper. The local cache
      is abstract-only, so it supports mitochondrial identity but not a granular
      quotation of the reported cellular colocalization assay.
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: >-
      The primary HuRI supplement and UniProt/IntAct independently confirm the
      EHHADH-AARS2 and PTPA-AARS2 binary pairs. The source provides no native-complex
      context or AARS2-specific mechanism, so it validates pair provenance but not a
      useful core molecular function.
- id: PMID:34800366
  title: Quantitative high-confidence human mitochondrial proteome and its dynamics
    in cellular context.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Full Supplementary Table S1 directly identifies Q5JTZ9/AARS2 in this dataset and
      assigns it to MitoCoP, with concordant subtractive, spatial and importomics
      classifications. This is valid high-throughput mitochondrial-localization evidence
      and is independently corroborated by targeted and biochemical studies.
- id: PMID:29228266
  title: Editing activity for eliminating mischarged tRNAs is essential in mammalian
    mitochondria.
  full_text_unavailable: false
  findings:
  - statement: >-
      Recombinant mature human AARS2 misactivates serine sufficiently to require
      proofreading.
    supporting_text: >-
      HmtAlaRS misactivated Ser with a discriminator factor of 1/569 (Table 1),
      which is significantly larger than 1/3300, the proposed threshold for
      frequency of errors in protein synthesis (31), suggesting that mtAlaRS
      requires editing function to prevent Ala-to-Ser misincorporation in
      mitochondria.
    reference_section_type: RESULTS
    full_text_unavailable: false
  - statement: >-
      Human AARS2 directly performs post-transfer editing of Ser-tRNAAla; editing-domain
      substitutions impair this activity while largely preserving charging.
    supporting_text: >-
      In vitro aminoacylation assay indicated that the mutants C749A and V760E
      displayed only slightly decreased tRNAAla charging activity compared with wild
      type mtAlaRS (Figure 1D). Determination of post-transfer editing of mischarged
      Ser-tRNAAla showed that the C749A mutant was severely defective in editing
      while the initial velocity of the post-transfer editing activity of the V760E
      mutant was only slightly reduced (Figure 1E and F).
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Primary direct evidence using recombinant mature human AARS2. The biochemical
      Ser-editing assays are human in vitro experiments; evidence that editing is
      essential in vivo comes from homozygous editing-deficient mouse knock-ins.
- id: PMID:30262995
  title: Overexpression of human mitochondrial alanyl-tRNA synthetase suppresses
    biochemical defects of the mt-tRNA(Ala) mutation in cybrids.
  full_text_unavailable: false
  findings:
  - statement: >-
      AARS2 overexpression increases charging of mutant human mt-tRNAAla and improves
      mitochondrial translation.
    supporting_text: >-
      In this study, AARS2 overexpression did not result in a detectable increase of
      the mutated mt-tRNAAla but caused an increase incharged mt-tRNAAla in mutant
      cybrids, leading to enhanced mitochondrial translation. This strongly suggested
      that AARS2 improved the aminoacylation activity rather than preventing the
      degradation of mt-tRNAAla 5655A>G.
    reference_section_type: DISCUSSION
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Human-cell evidence supporting mitochondrial mt-tRNAAla charging and downstream
      translation. The system consists of transmitochondrial cybrids carrying
      pathogenic m.5655A>G plus AARS2 overexpression, so it is rescue evidence rather
      than a basal wild-type kinetic assay. The cached text itself contains the word
      form "incharged" and it is retained verbatim.
- id: PMID:30285085
  title: Instability of the mitochondrial alanyl-tRNA synthetase underlies fatal
    infantile-onset cardiomyopathy.
  full_text_unavailable: false
  findings:
  - statement: >-
      The cardiomyopathy-associated p.Arg580Trp variant primarily destabilizes AARS2
      rather than abolishing its charging or editing chemistry.
    supporting_text: >-
      Taken together, our data suggest that the p.Arg580Trp variant impacts on
      stability of mt-AlaRS protein but not aminoacylation or editing activities and
      that the β-barrel subdomain has a critical role in protein folding and
      stability.
    reference_section_type: DISCUSSION
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Includes human patient fibroblast, skeletal-muscle and cardiac-tissue data,
      recombinant human enzyme assays, and HEK293T stability assays. The conclusion
      is variant-specific and must not be generalized to all AARS2 disease alleles.
- id: PMID:30952159
  title: The G3-U70-independent tRNA recognition by human mitochondrial alanyl-tRNA
    synthetase.
  full_text_unavailable: false
  findings:
  - statement: >-
      Human mitochondrial AARS2 is monomeric and recognizes mt-tRNAAla without the
      canonical G3-U70 identity pair.
    supporting_text: >-
      In the present study, we found that hmtAlaRS is a monomer and recognizes
      mitochondrial tRNAAla in a G3-U70-independent manner, requiring several
      elements in the acceptor stem.
    reference_section_type: ABSTRACT
    full_text_unavailable: false
  - statement: >-
      Human AARS2 misactivates glycine and has strong tRNA-independent pre-transfer
      editing against glycine.
    supporting_text: >-
      In addition, we found that hmtAlaRS misactivates noncognate Gly and catalyzes
      strong transfer RNA (tRNA)-independent pre-transfer editing for Gly.
    reference_section_type: ABSTRACT
    full_text_unavailable: false
  - statement: Human AARS2 also performs post-transfer editing of Gly-tRNAAla.
    supporting_text: >-
      However, it synthesized more mischarged Gly-tRNAAla than did the wild-type
      hmtAlaRS, comparable with our previously constructed editing-defective C749A
      (42) (Figure 5D and E), supporting its defect in editing. Indeed, the result of
      the post-transfer editing assay showed that hmtAlaRS-R663E was unable to
      hydrolyze Gly-tRNAAla (Figure 5F).
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Strongest direct support for human Gly-tRNAAla editing. Enzymology used
      recombinant human AARS2 and in-vitro-transcribed human mt-tRNAAla. Monomeric
      state was additionally tested by co-immunoprecipitation in HEK293T cells; the
      data do not support a stable-complex core function.
- id: PMID:32080176
  title: Relaxed sequence constraints favor mutational freedom in idiosyncratic
    metazoan mitochondrial tRNAs.
  full_text_unavailable: false
  findings:
  - statement: Purified human mitochondrial AARS2 selectively charges cognate mt-tRNAAla.
    supporting_text: >-
      Hs mt AlaRS charges cognate mt tRNAAla but not mt tRNAs specific for Asp, Leu,
      or Ser.
    reference_section_type: RESULTS
    full_text_unavailable: false
  - statement: >-
      The AARS2 C-Ala domain helps fold and recognize the structurally flexible human
      mitochondrial tRNAAla elbow.
    supporting_text: >-
      The appended C-Ala domain, which plays an auxiliary role in prokaryotic AlaRSs
      and is dispensable for aminoacylation in the human cytoplasmic AlaRS
      system43,44, plays a central role as a folding aid for the intrinsically
      flexible mt tRNA elbow. Fine-tuned induced-fit adaptation selects mt tRNAAla
      and rejects non-cognate mt tRNAs (Supplementary Fig. 7g).
    reference_section_type: DISCUSSION
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Direct human charging and substrate-discrimination evidence using purified
      mature AARS2 and unmodified in-vitro-transcribed tRNAs. Crystal structures
      concern isolated human C-Ala fragments; the full-length AARS2-tRNA complex was
      modeled rather than crystallized.
- id: PMID:38163844
  title: Hypoxia induces mitochondrial protein lactylation to limit oxidative
    phosphorylation.
  full_text_unavailable: false
  findings:
  - statement: >-
      Recombinant AARS2 directly catalyzes ATP- and lactate-dependent lactylation of
      PDHA1 and CPT2 substrate peptides.
    supporting_text: >-
      AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the
      K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b)
      via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.
    reference_section_type: RESULTS
    full_text_unavailable: false
  - statement: >-
      AARS2-dependent PDHA1 and CPT2 lactylation was observed under high-lactate
      conditions.
    supporting_text: >-
      Treatment with 10 mM Me-Lac increased the Lac-K336 and Lac-K457/8 levels of
      ectopically expressed PDHA1 (Fig. 5d) and CPT2 (Fig. 5e) in C2C12 and HL-1
      cells (Supplementary information, Fig. S6g). However, the lactylation was not
      observed when Aars2 was knocked out (Fig. 5d, e).
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Direct support for conditional AARS2 lactyltransferase activity, with hypoxia
      and high lactate as central contexts. Cellular physiology and in-vivo evidence
      are predominantly from mouse cells and mice. Cytoplasmic AARS2 detected during
      hypoxia was also in mouse cells and is not direct basal human localization
      evidence.
- id: PMID:39322678
  title: AARS1 and AARS2 sense L-lactate to regulate cGAS as global lysine lactyltransferases.
  full_text_unavailable: true
  findings:
  - statement: >-
      AARS1 and AARS2 bind L-lactate and directly catalyze ATP-dependent lysine
      lactylation.
    supporting_text: >-
      Here we identify the alanyl-tRNA synthetases AARS1 and AARS2 (AARS1/2) as
      intracellular L-lactate sensors required for L-lactate to stimulate the lysine
      lactylome in cells. AARS1/2 and the evolutionarily conserved Escherichia coli
      orthologue AlaRS bind to L-lactate with micromolar affinity and they directly
      catalyse L-lactate for ATP-dependent lactylation on the lysine acceptor end.
    reference_section_type: ABSTRACT
    full_text_unavailable: true
  - statement: >-
      Under elevated L-lactate, AARS2 associates with and lactylates cGAS, inhibiting
      cGAS.
    supporting_text: >-
      In response to L-lactate, AARS2 associates with cyclic GMP-AMP synthase (cGAS)
      and mediates its lactylation and inactivation in cells and in mice.
    reference_section_type: ABSTRACT
    full_text_unavailable: true
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Supports a conditional noncanonical lactyltransferase role and cGAS regulation.
      The local cache is abstract-only, so exact cell identities, human-versus-mouse
      experimental allocation, and compartmental access cannot be fully audited. It
      does not by itself establish basal global dominance or routine nuclear/cytosolic
      localization of mature AARS2.
- id: PMID:40835008
  title: Class I histone deacetylases catalyze lysine lactylation.
  full_text_unavailable: false
  findings:
  - statement: >-
      AARS1 or AARS2 depletion does not reduce global basal lysine lactylation in the
      untreated proliferating HEK293T model.
    supporting_text: >-
      To compare the relative contribution of AARS enzymes towards global basal
      levels of Kla in cells, we used siRNA to knockdown AARS1 and AARS2. However,
      the knockdown of either enzyme did not alter Kla levels (Fig. S6, B–E),
      suggesting the AARS pathway is also not required for global lysine lactylation.
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Essential counter-scope for the global-lactyltransferase framing. This result
      concerns global basal Kla in untreated proliferating HEK293T cells and does not
      refute target-specific AARS2 activity under hypoxia, high lactate, glucose
      starvation, or other induced conditions.
- id: PMID:40301335
  title: AARS2-catalyzed lactylation induces follicle development and premature
    ovarian insufficiency.
  full_text_unavailable: false
  findings:
  - statement: >-
      AARS2-dependent PDHA1/CPT2 lactylation occurs in a human granulosa-cell model,
      and the POI-associated R199C variant has increased activity.
    supporting_text: >-
      AARS2 deletion abrogated PDHA1 K336 and CPT2 K457/8 lactylation in the human
      granulosa cell line COV343 [38], and R199C exhibited a higher ability to
      lactylate PDHA1 K336 and CPT2 K457/8 in AARS2−/− COV343 cells (Fig. 3A, B).
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Human-cell and recombinant-protein evidence for conditional substrate-specific
      lactyltransferase activity, centered on ovarian disease variants and supported
      in vivo by mouse ovarian models. The prose calls the line COV343 whereas the
      adjacent figure legend calls it COV434; the cached quote is preserved while the
      internal model-label inconsistency is flagged.
- id: PMID:24808023
  title: Novel (ovario) leukodystrophy related to AARS2 mutations.
  full_text_unavailable: false
  findings:
  - statement: >-
      Selected leukodystrophy-associated AARS2 variants were functionally assessed
      through a recombinant yeast model.
    supporting_text: >-
      The pathogenicity of the 2 AARS2 variants of P1 was proven in a recombinant
      yeast model.
    reference_section_type: DISCUSSION
    full_text_unavailable: false
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Establishes the broader human AARS2 disease spectrum, but its functional assay
      is yeast complementation and respiratory-chain analysis rather than direct
      human AARS2 charging or editing. Disease phenotypes are not core molecular
      functions.
- id: PMID:42010330
  title: PCBP1 regulates alternative splicing of AARS2 in congenital cardiomyopathy.
  full_text_unavailable: false
  findings:
  - statement: >-
      PCBP1-binding motifs and human PCBP1 are required for inclusion of AARS2 exon
      16 in human cell-based minigene assays.
    supporting_text: >-
      We found that mutations of either PCBP1 site 1 or site 2, or canonical splice
      donor or acceptor sites, are sufficient to cause exclusion of AARS2 exon-16
      (Fig. 1l,m). Knockdown of human PCBP1 in both systems shows a similar pattern
      of AARS2 exon-16 exclusion (Fig. 1l,m and Extended Data Fig. 1c).
    reference_section_type: RESULTS
    full_text_unavailable: false
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: >-
      Human AARS2 exon-16 minigenes were tested in HEK293T cells and hiPSC-derived
      cardiomyocytes; extensive causal heart-development and OXPHOS evidence comes
      from mouse conditional genetics. This supports regulated transcript processing
      and a loss-of-function disease mechanism, not a distinct stable AARS2 protein
      isoform with a proven alternative activity.
- id: Reactome:R-HSA-380177
  title: alanine + tRNA(Ala) + ATP => Ala-tRNA(Ala) + AMP + pyrophosphate
  findings:
  - statement: >-
      Reactome represents AARS2-catalyzed mitochondrial alanine-tRNA charging.
    supporting_text: >-
      AARS2 (mitochondrial alanyl tRNA synthetase) catalyzes the reaction of alanine,
      mitochondrial tRNA(Ala), and ATP to form Ala-tRNA(Ala), AMP, and pyrophosphate.
    reference_section_type: DATABASE_ENTRY
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      The reaction chemistry and mitochondrial substrate are correct and match later
      direct human biochemical evidence. Reactome explicitly states that this event
      was originally inferred computationally from other characterized mitochondrial
      tRNA synthetases, so it is pathway/database support rather than independent
      experimental evidence for AARS2.
- id: file:human/AARS2/AARS2-uniprot.txt
  title: UniProtKB/Swiss-Prot record for human AARS2 (Q5JTZ9)
  findings:
  - statement: >-
      UniProt records alanine charging and editing of incorrectly charged tRNAAla as
      AARS2's canonical functions.
    supporting_text: |-
      CC   -!- FUNCTION: Catalyzes the attachment of alanine to tRNA(Ala) in a two-
      CC       step reaction: alanine is first activated by ATP to form Ala-AMP and
      CC       then transferred to the acceptor end of tRNA(Ala). Also edits
      CC       incorrectly charged tRNA(Ala) via its editing domain (PubMed:21549344).
    reference_section_type: DATABASE_ENTRY
  - statement: UniProt locates the reviewed AARS2 product in mitochondria.
    supporting_text: |-
      CC   -!- SUBCELLULAR LOCATION: Mitochondrion {ECO:0000255|HAMAP-Rule:MF_03133,
      CC       ECO:0000269|PubMed:21549344}.
    reference_section_type: DATABASE_ENTRY
  - statement: >-
      UniProt flags the unresolved compartmental access underlying AARS2-mediated
      cGAS lactylation.
    supporting_text: |-
      CC   -!- CAUTION: Given that AARS2 is a mitochondrial protein, it is unclear how
      CC       it can mediate lactylation of CGAS, which localizes in the cytosol and
      CC       nucleus. {ECO:0000269|PubMed:39322678}.
    reference_section_type: DATABASE_ENTRY
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: >-
      Authoritative reviewed record for Q5JTZ9. Its charging/editing and mitochondrial
      localization summary agrees with the direct literature. Its lactyltransferase
      summary is correctly restricted to high lactate, and its explicit compartmental
      caution is retained; the entry is not used to infer basal global lactylation or
      routine extramitochondrial localization.
core_functions:
- description: >-
    In mitochondria, AARS2 activates L-alanine with ATP and transfers it to mitochondrial
    tRNA(Ala), producing Ala-tRNA(Ala) for mitochondrial translation. This organelle-
    specific aminoacylation reaction is the enzyme's primary conserved activity.
  supported_by:
  - reference_id: PMID:32080176
    supporting_text: >-
      Hs mt AlaRS charges cognate mt tRNAAla but not mt tRNAs specific for Asp, Leu,
      or Ser.
  - reference_id: PMID:30262995
    supporting_text: >-
      In this study, AARS2 overexpression did not result in a detectable increase of
      the mutated mt-tRNAAla but caused an increase incharged mt-tRNAAla in mutant
      cybrids, leading to enhanced mitochondrial translation. This strongly suggested
      that AARS2 improved the aminoacylation activity rather than preventing the
      degradation of mt-tRNAAla 5655A>G.
  molecular_function:
    id: GO:0004813
    label: alanine-tRNA ligase activity
  directly_involved_in:
  - id: GO:0070143
    label: mitochondrial alanyl-tRNA aminoacylation
  locations:
  - id: GO:0005739
    label: mitochondrion
- description: >-
    The embedded AARS2 editing apparatus proofreads mitochondrial tRNA(Ala) and
    hydrolyzes incorrectly attached serine and glycine. Direct human assays establish
    post-transfer Ser-tRNA(Ala) and Gly-tRNA(Ala) deacylation; glycine errors are also
    strongly cleared before transfer. Together these activities protect mitochondrial
    translational fidelity.
  supported_by:
  - reference_id: PMID:29228266
    supporting_text: >-
      Determination of post-transfer editing of mischarged Ser-tRNAAla showed that
      the C749A mutant was severely defective in editing while the initial velocity
      of the post-transfer editing activity of the V760E mutant was only slightly
      reduced (Figure 1E and F).
  - reference_id: PMID:30952159
    supporting_text: >-
      Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E
      was unable to hydrolyze Gly-tRNAAla (Figure 5F).
  molecular_function:
    id: GO:0002161
    label: aminoacyl-tRNA deacylase activity
  directly_involved_in:
  - id: GO:0106074
    label: aminoacyl-tRNA metabolism involved in translational fidelity
  locations:
  - id: GO:0005739
    label: mitochondrion
- description: >-
    As a conditional secondary activity under hypoxia or elevated intracellular
    lactate, AARS2 uses lactate and ATP to transfer lactyl groups to protein lysines.
    Directly demonstrated mitochondrial substrates include PDHA1 and CPT2. This is a
    context- and substrate-dependent activity rather than a basal global role: AARS2
    depletion does not lower global lysine lactylation in untreated HEK293T cells.
    The reported cGAS signaling outcome is non-core because the route by which
    mitochondrial AARS2 encounters cytosolic or nuclear cGAS remains unresolved.
  supported_by:
  - reference_id: PMID:38163844
    supporting_text: >-
      AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the
      K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b)
      via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.
  molecular_function:
    id: GO:0141207
    label: peptide lactyltransferase (ATP-dependent) activity
  locations:
  - id: GO:0005739
    label: mitochondrion
knowledge_gaps:
- gap_statement: >-
    The relative in vivo contributions of AARS2 pre-transfer and post-transfer editing
    to clearance of glycine errors, and the physiological balance between glycine and
    serine mischarging of mitochondrial tRNA(Ala), remain unresolved in human cells.
  boundary: >-
    Purified human AARS2 directly edits both Gly-tRNA(Ala) and Ser-tRNA(Ala), with
    biochemical evidence for strong glycine pre-transfer editing and post-transfer
    hydrolysis of both mischarged products. These assays establish the activities but
    do not quantify their separate contributions under endogenous mitochondrial
    substrate concentrations.
  gap_kind:
  - BIOLOGY
  dark_aspect: RESIDUAL_SUBGAP
  status: OPEN
  significance: >-
    Resolving the editing pathway used for each error would clarify which proofreading
    defect drives mitochondrial mistranslation in different AARS2 alleles and metabolic
    states.
  resolution: >-
    Use separation-of-function AARS2 variants in human cells and directly quantify
    aminoacylated and mischarged mitochondrial tRNA(Ala), together with Ala-to-Ser and
    Ala-to-Gly substitutions in newly synthesized mitochondrial proteins.
  provenance:
  - reference_id: PMID:29228266
    supporting_text: >-
      Determination of post-transfer editing of mischarged Ser-tRNAAla showed that
      the C749A mutant was severely defective in editing while the initial velocity
      of the post-transfer editing activity of the V760E mutant was only slightly
      reduced (Figure 1E and F).
  - reference_id: PMID:30952159
    supporting_text: >-
      Indeed, the result of the post-transfer editing assay showed that hmtAlaRS-R663E
      was unable to hydrolyze Gly-tRNAAla (Figure 5F).
- gap_statement: >-
    The physiological lactate range, cell states, tissues, and substrate spectrum in
    which endogenous AARS2 materially contributes to protein lysine lactylation,
    relative to class I HDACs and other routes, remain incompletely defined.
  boundary: >-
    AARS2-dependent lactylation of PDHA1 and CPT2 is supported under exercise-, hypoxia-,
    or lactate-associated conditions, whereas AARS2 knockdown does not reduce basal
    global lysine lactylation in untreated HEK293T cells.
  gap_kind:
  - BIOLOGY
  - CURATION
  dark_aspect: RESIDUAL_SUBGAP
  status: OPEN
  significance: >-
    A quantitative boundary is needed to distinguish physiological AARS2 substrates
    from high-lactate or overexpression effects and to avoid generalizing a conditional,
    target-specific activity to the basal lactylome.
  resolution: >-
    Quantify endogenous site-resolved lactylation across calibrated intracellular
    lactate and oxygen ranges after acute AARS2 depletion and matched rescue, alongside
    class I HDAC perturbation and measurements of mitochondrial alanine charging.
  provenance:
  - reference_id: PMID:38163844
    supporting_text: >-
      AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the
      K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b)
      via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.
  - reference_id: PMID:40835008
    supporting_text: >-
      However, the knockdown of either enzyme did not alter Kla levels (Fig. S6, B–E),
      suggesting the AARS pathway is also not required for global lysine lactylation.
- gap_statement: >-
    How a mitochondrial AARS2 pool accesses cytosolic or nuclear cGAS for the reported
    lactate-responsive modification is unknown, and no stable extramitochondrial AARS2
    pool or trafficking mechanism has been established.
  boundary: >-
    Reviewed localization evidence places AARS2 in mitochondria, while a cGAS study
    reports AARS2-dependent cGAS lactylation. The compartmental mismatch is explicitly
    unresolved and does not justify assigning a routine cytosolic or nuclear location.
  gap_kind:
  - BIOLOGY
  - CURATION
  dark_aspect: RESIDUAL_SUBGAP
  status: OPEN
  significance: >-
    Defining the relevant AARS2 species and compartment is necessary to distinguish a
    direct signaling mechanism from indirect metabolic effects and to curate cellular
    locations without over-annotation.
  resolution: >-
    Endogenously tag AARS2 and resolve its precursor and mature forms by quantitative
    fractionation, protease protection, and live-cell imaging during lactate exposure;
    combine this with AARS2-cGAS proximity labeling and mitochondrial-import perturbation.
  provenance:
  - reference_id: file:human/AARS2/AARS2-uniprot.txt
    supporting_text: >-
      CC   -!- CAUTION: Given that AARS2 is a mitochondrial protein, it is unclear how
      CC       it can mediate lactylation of CGAS, which localizes in the cytosol and
      CC       nucleus. {ECO:0000269|PubMed:39322678}.
proposed_new_terms:
- proposed_name: peptidyl-lysine lactylation
  proposed_definition: >-
    A peptidyl-lysine modification process in which a lactyl group is covalently added
    to the epsilon-amino group of a lysine residue within a protein.
  justification: >-
    GO:0141207 captures the ATP-dependent molecular activity but no current biological
    process term captures its immediate protein-modification outcome. The proposed term
    should be placed under GO:0018205 peptidyl-lysine modification and related to the
    broader GO:0043543 protein acylation branch; it would support curation of AARS2 and
    other experimentally established lysine lactylation mechanisms without conflating
    them with downstream signaling phenotypes. A live QuickGO ontology search on
    2026-08-08 found related delactylase activities but no peptidyl-lysine lactylation
    biological-process term.
  proposed_parent:
    id: GO:0018205
    label: peptidyl-lysine modification
  supported_by:
  - reference_id: PMID:38163844
    supporting_text: >-
      AARS2 lactylated the synthetic K336-containing PDHA1 peptide as well as the
      K457/8-containing CPT2 peptide (Fig. 5b; Supplementary information, Fig. S6b)
      via lactate- and ATP-dependent and pyrophosphate-inhibitable mechanisms.
suggested_questions:
- question: >-
    In human mitochondria, what fractions of glycine and serine errors are prevented
    by AARS2 pre-transfer editing versus cleared by post-transfer deacylation under
    physiological substrate concentrations?
  experts: []
- question: >-
    Across physiological and pathological lactate concentrations, which endogenous
    protein substrates depend materially on AARS2 rather than class I HDACs or other
    lactylation routes, and in which tissues and cell states?
  experts: []
- question: >-
    What AARS2 species and trafficking mechanism permit direct encounter with cGAS,
    and does this involve the mitochondrial precursor, the mature enzyme, or an
    inducible extramitochondrial pool?
  experts: []
suggested_experiments:
- hypothesis: >-
    AARS2 uses mechanistically distinct proofreading routes for glycine and serine
    errors that make different contributions to mitochondrial translational fidelity
    in human cells.
  description: >-
    Introduce matched separation-of-function AARS2 variants into an acute AARS2-depletion
    background, then quantify charging and mischarging of mitochondrial tRNA(Ala) and
    Ala-to-Gly or Ala-to-Ser substitutions in pulse-labeled mitochondrial translation
    products. Complement the cell measurements with pre-transfer and single-turnover
    post-transfer kinetics using purified human AARS2.
  experiment_type: mitochondrial tRNA biochemistry and quantitative mitoproteomics
- hypothesis: >-
    Endogenous AARS2 contributes substantially to a restricted, high-lactate
    mitochondrial lactylome but not to basal global lysine lactylation.
  description: >-
    Use acute endogenous AARS2 degradation across calibrated intracellular lactate and
    oxygen ranges, followed by isotope-resolved quantitative lactyl-proteomics and
    targeted measurement of PDHA1 K336 and CPT2 K457/K458. Rescue with matched-expression
    AARS2 variants that retain alanine charging but differ in lactyltransferase activity,
    and compare with class I HDAC perturbation.
  experiment_type: acute perturbation and quantitative lactyl-proteomics
- hypothesis: >-
    A lactate-responsive AARS2 precursor or inducible extramitochondrial species directly
    encounters cGAS, whereas the mature mitochondrial pool does not.
  description: >-
    Endogenously tag both termini of AARS2, distinguish precursor from mature protein,
    and combine quantitative fractionation, protease protection, live-cell imaging,
    and cGAS-directed proximity labeling before and after lactate exposure. Perturb the
    mitochondrial targeting sequence and import machinery while measuring site-specific
    cGAS lactylation and cGAS-STING signaling, with charging-competent rescue controls.
  experiment_type: compartment-resolved trafficking and proximity analysis

AARS2

Gene Description

Proposed New Ontology Terms

peptidyl-lysine lactylation

Existing Annotations Review

Core Functions

In mitochondria, AARS2 activates L-alanine with ATP and transfers it to mitochondrial tRNA(Ala), producing Ala-tRNA(Ala) for mitochondrial translation. This organelle- specific aminoacylation reaction is the enzyme's primary conserved activity.

References

Suggested Questions for Experts

Suggested Experiments

Knowledge Gaps

📚 Additional Documentation

Notes

AARS2 review notes

Research provenance

Functional evidence map

Curation priorities

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