ATP6V0A2

UniProt ID: Q9Y487
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

ATP6V0A2 encodes the a2 isoform of the V-type proton ATPase 116 kDa a-subunit, an integral membrane component of the V0 proton-translocation sector of the V-ATPase. The protein helps assemble and position V-ATPase activity in acidic intracellular compartments, especially early endosomes and Golgi/endolysosomal membranes, where the complex acidifies organelle lumens to support membrane trafficking, protein degradation, lysosomal function, and Golgi-dependent glycosylation. ATP6V0A2 also participates in endosomal pH-sensing through an acidification-dependent interaction with ARNO/PSCD2, and disruption of V-ATPase function affects intracellular iron availability and HIF prolyl hydroxylation. Biallelic ATP6V0A2 variants cause autosomal recessive cutis laxa type 2A and wrinkly skin syndrome with glycosylation defects.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0016471 vacuolar proton-transporting V-type ATPase complex
IBA
GO_REF:0000033
ACCEPT
Summary: ATP6V0A2 encodes the a2 isoform of the V0 membrane sector of the V-ATPase. Complex membership is a core cellular-component annotation supported by UniProt curation and human V-ATPase structural literature.
Reason: The annotation correctly places ATP6V0A2 in the vacuolar proton-transporting V-type ATPase complex. The protein is a V0 a-subunit of a multisubunit proton pump, and the V0 sector is the membrane proton-translocation module of the complex.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0046961 proton-transporting ATPase activity, rotational mechanism
IBA
GO_REF:0000033
ACCEPT
Summary: ATP6V0A2 contributes to the rotational V-ATPase proton-pumping activity as a V0 membrane-sector subunit, but does not independently hydrolyze ATP outside the assembled complex.
Reason: The contributes_to qualifier is appropriate for a subunit of the V-ATPase complex. The complex couples ATP hydrolysis in V1 to proton transfer through V0, and ATP6V0A2 is a V0 a-subunit.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0005886 plasma membrane
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: Plasma-membrane localization is plausible for V-ATPase a-subunits in some cell contexts, but ATP6V0A2 is better established in endosomal, Golgi, and lysosomal/vesicular membranes.
Reason: UniProt includes cell-membrane localization and the GOA contains HPA plasma-membrane evidence, so the annotation is not rejected. It should not be treated as the main proteostasis-relevant location for ATP6V0A2, whose strongest mechanistic evidence is in intracellular acidic compartments.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Cell membrane; Multi-pass membrane protein.
PMID:16415858
The a2-isoform is targeted to early endosomes
GO:0007035 vacuolar acidification
IBA
GO_REF:0000033
ACCEPT
Summary: Vacuolar acidification is a correct broad biological-process annotation for ATP6V0A2 as a V-ATPase V0 subunit involved in acidification of acidic intracellular compartments.
Reason: The term captures the core acidification role of the V-ATPase. For the PN batch, lysosomal lumen acidification is added separately as a more specific supported annotation, but the existing broad annotation remains biologically sound.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments
PMID:32001091
V-ATPases are the primary source of organellar acidification in all eukaryotes
PMID:33065002
organellar V-ATPases are essential in establishing and maintaining the pH
GO:0051117 ATPase binding
IBA
GO_REF:0000033
MARK AS OVER ANNOTATED
Summary: ATPase binding is much less informative than the complex-membership and contributes_to V-ATPase activity annotations already present for ATP6V0A2.
Reason: ATP6V0A2 functions as an integral V0-sector subunit. Treating ATPase binding as a gene-level molecular function risks reducing complex assembly/participation to a vague binding annotation; the more informative annotations are V-ATPase complex/V0-domain membership and contribution to proton-pumping ATPase activity.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0000220 vacuolar proton-transporting V-type ATPase, V0 domain
IEA
GO_REF:0000002
ACCEPT
Summary: The vacuolar V-ATPase V0-domain annotation matches ATP6V0A2 family/domain evidence and its role as an integral membrane V0 a-subunit.
Reason: ATP6V0A2 is a member of the V-ATPase 116 kDa subunit family and is curated as a V0-complex subunit. The broader V0-domain annotation is correct; the PN-derived lysosomal V0-domain annotation is added separately where lysosomal localization is supported.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Belongs to the V-ATPase 116 kDa subunit family.
GO:0005886 plasma membrane
IEA
GO_REF:0000044
KEEP AS NON CORE
Summary: Plasma-membrane localization is supported by UniProt/HPA-derived evidence but is secondary to the intracellular organelle acidification role.
Reason: The location is plausible and appears in curated resources, but the literature most directly supporting ATP6V0A2 function emphasizes early endosomes, Golgi function, and endolysosomal acidification rather than a primary plasma-membrane role.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Cell membrane; Multi-pass membrane protein.
PMID:16415858
The a2-isoform is targeted to early endosomes
GO:0010008 endosome membrane
IEA
GO_REF:0000044
ACCEPT
Summary: ATP6V0A2 is well supported at the endosome membrane, especially early endosomes, where a2-containing V-ATPase contributes to pH sensing and endocytic trafficking.
Reason: The UniProt-derived IEA annotation is consistent with direct literature showing the a2 isoform is targeted to early endosomes and participates in intra-endosomal acidification-dependent ARNO recruitment and endocytic trafficking.
Supporting Evidence:
PMID:16415858
The a2-isoform is targeted to early endosomes
PMID:16415858
interacts with ARNO in an intra-endosomal acidification-dependent manner
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Essential component of the endosomal pH-sensing machinery
GO:0033179 proton-transporting V-type ATPase, V0 domain
IEA
GO_REF:0000120
ACCEPT
Summary: The V0-domain annotation is a core cellular-component annotation for ATP6V0A2.
Reason: ATP6V0A2 is the a2 isoform of the V-ATPase 116 kDa a-subunit and belongs to the V0 membrane proton-transfer sector. This term is already aligned with the PN V0 component projection, although PN also supports a lysosomal-specific child term.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0046961 proton-transporting ATPase activity, rotational mechanism
IEA
GO_REF:0000002
MODIFY
Summary: The V-ATPase rotational proton-pump activity is correct for the assembled ATP6V0A2-containing complex. ATP6V0A2 should be interpreted as contributing to this activity as a V0 subunit rather than acting as an independent ATPase.
Reason: The term is biologically appropriate for ATP6V0A2-containing V-ATPase complexes, but the GOA qualifier should be changed from enables to contributes_to. The contributes_to IBA qualifier is the clearest representation of a single V0 subunit's contribution to the assembled proton pump.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:1902600 proton transmembrane transport
IEA
GO_REF:0000002
ACCEPT
Summary: ATP6V0A2 participates in proton transmembrane transport as part of the V-ATPase proton-translocation machinery.
Reason: The V0 sector transfers protons across organelle membranes as part of the V-ATPase. ATP6V0A2 is a V0 a-subunit in this machinery, so the process annotation is appropriate.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0005515 protein binding
IPI
PMID:16415858
V-ATPase interacts with ARNO and Arf6 in early endosomes and...
REMOVE
Summary: PMID:16415858 supports a specific ARNO interaction with the a2 isoform, but GO:0005515 protein binding is too generic to retain as useful functional annotation.
Reason: The interaction evidence is real, but generic protein binding is uninformative and is explicitly discouraged in this review workflow. The functional meaning of the interaction is better captured in the review text as endosomal pH-sensing/trafficking, not as GO:0005515.
Supporting Evidence:
PMID:16415858
interacts with ARNO in an intra-endosomal acidification-dependent manner
PMID:16415858
Inhibition of endosomal acidification abrogates protein trafficking between
GO:0001669 acrosomal vesicle
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Acrosomal-vesicle localization is plausible by orthology for V-ATPase a-subunits but is not part of the core ATP6V0A2 proteostasis role reviewed here.
Reason: The annotation comes from Ensembl orthology transfer rather than direct ATP6V0A2 literature in this review. It is retained as a possible specialized reproductive-cell location, but the main supported locations are endosome, Golgi, lysosomal, and other acidic-vesicle membranes.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
GO; GO:0001669; C:acrosomal vesicle; IEA:Ensembl.
GO:0015078 proton transmembrane transporter activity
IEA
GO_REF:0000107
ACCEPT
Summary: ATP6V0A2 contributes to proton transmembrane transporter activity as a V0 membrane-sector component of the assembled V-ATPase.
Reason: The contributes_to qualifier is appropriate for ATP6V0A2 because proton translocation is performed by the assembled V-ATPase/V0 machinery rather than by the isolated subunit.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0033176 proton-transporting V-type ATPase complex
IEA
GO_REF:0000107
ACCEPT
Summary: The broader proton-transporting V-type ATPase complex annotation is correct for ATP6V0A2.
Reason: ATP6V0A2 is an integral V0-sector subunit of the V-ATPase. The annotation is less specific than the V0-domain annotations but remains valid complex membership.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
GO:0048471 perinuclear region of cytoplasm
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Perinuclear-region localization is compatible with Golgi/endosomal distribution but is not the most informative cellular-component annotation for ATP6V0A2.
Reason: The annotation is retained as a broad localization transferred by Ensembl, but more precise experimentally supported locations include endosome membrane, Golgi membrane, and lysosomal membrane.
Supporting Evidence:
PMID:16415858
The a2-isoform is targeted to early endosomes
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
May play a role in maintaining the Golgi functions
GO:0005886 plasma membrane
IDA
GO_REF:0000052
KEEP AS NON CORE
Summary: HPA reports ATP6V0A2 at the plasma membrane, but this is a secondary location relative to intracellular acidic compartments.
Reason: The IDA evidence supports retaining the localization, but the core functional literature for ATP6V0A2 centers on endosomal/Golgi/lysosomal acidification and V-ATPase complex function.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
GO; GO:0005886; C:plasma membrane; IDA:HPA.
GO:0000139 Golgi membrane
NAS
PMID:32001091
Structure and Roles of V-type ATPases.
ACCEPT
Summary: Golgi membrane localization is consistent with ATP6V0A2 disease biology and Golgi acidification/glycosylation functions.
Reason: ATP6V0A2 is implicated in maintaining Golgi pH-dependent functions, including glycosylation maturation. ComplexPortal and review evidence support Golgi-membrane assignment for the ATP6V0A2-containing V-ATPase variant.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
May play a role in maintaining the Golgi functions, such as glycosylation maturation, by controlling the Golgi pH
PMID:32001091
V-ATPases are the primary source of organellar acidification in all eukaryotes
GO:0033176 proton-transporting V-type ATPase complex
NAS
PMID:33065002
Structures of a Complete Human V-ATPase Reveal Mechanisms of...
ACCEPT
Summary: Human V-ATPase structural literature supports ATP6V0A2 as part of a proton-transporting V-type ATPase complex.
Reason: The annotation captures the assembled complex in which ATP6V0A2 acts. Human V-ATPase structures define a V1 ATP-hydrolysis complex and a Vo proton-transfer complex.
Supporting Evidence:
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
GO:0061795 Golgi lumen acidification
NAS
PMID:32001091
Structure and Roles of V-type ATPases.
ACCEPT
Summary: Golgi lumen acidification is a supported ATP6V0A2-associated process and explains the glycosylation defects seen when ATP6V0A2 is disrupted.
Reason: UniProt and review evidence support ATP6V0A2 involvement in Golgi pH control and glycosylation maturation. This is a meaningful organelle-specific acidification annotation, not merely a broad proteostasis projection.
Supporting Evidence:
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
May play a role in maintaining the Golgi functions, such as glycosylation maturation, by controlling the Golgi pH
PMID:32001091
V-ATPases are the primary source of organellar acidification in all eukaryotes
GO:1902600 proton transmembrane transport
NAS
PMID:33065002
Structures of a Complete Human V-ATPase Reveal Mechanisms of...
ACCEPT
Summary: Proton transmembrane transport is the fundamental transport process mediated by the assembled V-ATPase containing ATP6V0A2.
Reason: The human V-ATPase is an ATP-driven proton pump with a Vo membrane complex for proton transfer, and ATP6V0A2 is one of the Vo a-subunits.
Supporting Evidence:
PMID:33065002
V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments
GO:0006879 intracellular iron ion homeostasis
IMP
PMID:28296633
The vacuolar-ATPase complex and assembly factors, TMEM199 an...
KEEP AS NON CORE
Summary: ATP6V0A2 disruption was identified in a V-ATPase/HIF screen, and the study supports a non-core role for V-ATPase function in intracellular iron availability and HIF prolyl hydroxylation.
Reason: The evidence is direct enough to retain the annotation, but intracellular iron homeostasis is downstream of the core V-ATPase acidification role rather than the primary evolved function of ATP6V0A2.
Supporting Evidence:
PMID:28296633
ATP6AP1, ATP6V1A, ATP6V1G1, ATP6V0A2 and ATP6V0D1
PMID:28296633
disrupting the V-ATPase results in intracellular iron depletion
GO:0036295 cellular response to increased oxygen levels
IMP
PMID:28296633
The vacuolar-ATPase complex and assembly factors, TMEM199 an...
MARK AS OVER ANNOTATED
Summary: The PMID:28296633 evidence supports V-ATPase effects on HIF stability under aerobic conditions through iron/PHD activity, but the GO term frames this too broadly as a response to increased oxygen levels.
Reason: ATP6V0A2 depletion affects HIF1A regulation indirectly through V-ATPase-dependent iron homeostasis. The paper explicitly argues against a lysosomal-degradation mechanism and focuses on PHD activity; the broad oxygen-response term should not be treated as a core ATP6V0A2 function.
Supporting Evidence:
PMID:28296633
ATP6AP1, ATP6V1A, ATP6V1G1, ATP6V0A2 and ATP6V0D1
PMID:28296633
disrupting the V-ATPase results in intracellular iron depletion
PMID:28296633
Rather than preventing the lysosomal degradation of HIF1Ξ±, the V-ATPase inhibition stabilised HIF1Ξ± by decreasing PHD enzymatic activity.
GO:0016241 regulation of macroautophagy
NAS
PMID:22982048
Lipofuscin is formed independently of macroautophagy and lys...
MARK AS OVER ANNOTATED
Summary: The macroautophagy annotation is too broad for ATP6V0A2. V-ATPase acidification supports lysosomal degradation/autophagic flux, but PMID:22982048 does not establish ATP6V0A2 as a specific regulator of macroautophagy.
Reason: The supporting paper discusses lipofuscin, autophagy, and lysosomal activity rather than ATP6V0A2-specific regulation of macroautophagy. For the PN batch, ATP6V0A2 should be represented by lysosomal acidification/V-ATPase component terms, not by a generic macroautophagy regulation term.
Supporting Evidence:
PMID:22982048
both the autophagosomes and the lysosomal system are not mandatory
GO:0005765 lysosomal membrane
HDA
PMID:17897319
Integral and associated lysosomal membrane proteins.
ACCEPT
Summary: Lysosomal membrane localization is supported by lysosomal membrane proteomics and is important for the PN lysosomal V-ATPase projection.
Reason: ATP6V0A2 is part of the V-ATPase system, and lysosomal membrane proteomics detected vacuolar ATPase-associated polypeptides in purified lysosomal membranes. This supports retaining the lysosomal membrane annotation and adding lysosomal V0-domain specificity.
Supporting Evidence:
PMID:17897319
17 polypeptides comprising or associated with the vacuolar adenosine
file:human/ATP6V0A2/ATP6V0A2-deep-research-manual.md
Both projected terms are accepted conservatively in the review because they are supported by ATP6V0A2 V0-subunit identity, lysosomal membrane evidence, and the broader human V-ATPase endosome/lysosome acidification literature.
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
GO:0030670 phagocytic vesicle membrane
TAS
Reactome:R-HSA-1222516
KEEP AS NON CORE
Summary: Phagocytic vesicle membrane localization is supported by Reactome V-ATPase phagosome acidification context but is a context-specific location rather than ATP6V0A2 core identity.
Reason: The V-ATPase acidifies phagosomes, but ATP6V0A2-specific evidence is indirect through Reactome complex membership. Retain as a specialized acidic-vesicle context, not as a main gene function.
Supporting Evidence:
Reactome:R-HSA-1222516
movement of three protons into the phagosome
GO:0010008 endosome membrane
TAS
Reactome:R-HSA-5252133
ACCEPT
Summary: Reactome places ATP6V0A2-containing V-ATPase context at endosome membranes during ATP6AP1/V-ATPase binding and acidification-related events.
Reason: Endosome membrane localization is well supported by both primary literature and Reactome event context; ATP6V0A2 is targeted to early endosomes and participates in pH-dependent trafficking.
Supporting Evidence:
Reactome:R-HSA-5252133
Vacuolar-type H+-ATPases (V-ATPases) are proton pumps that acidify intracellular cargos
PMID:16415858
The a2-isoform is targeted to early endosomes
GO:0010008 endosome membrane
TAS
Reactome:R-HSA-74723
ACCEPT
Summary: Endosome membrane localization is supported by the Reactome endosome acidification event and direct early-endosome literature for the a2 isoform.
Reason: The annotation matches ATP6V0A2 involvement in endosomal acidification and pH-dependent endocytic trafficking.
Supporting Evidence:
Reactome:R-HSA-74723
The effect of the proton pump is to allow entry of [H+] ions into the lumen of the endosome.
PMID:16415858
The a2-isoform is targeted to early endosomes
PMID:16415858
Inhibition of endosomal acidification abrogates protein trafficking between
GO:0010008 endosome membrane
TAS
Reactome:R-HSA-917841
ACCEPT
Summary: Endosome membrane localization is supported by Reactome transferrin-receptor endosome acidification context and by direct literature on the a2 isoform in early endosomes.
Reason: ATP6V0A2-containing V-ATPase participates in acidifying endosomal compartments, including transferrin-receptor recycling/endosome contexts in Reactome.
Supporting Evidence:
Reactome:R-HSA-917841
When pumping, ATP hydrolysis drives a 120 degree rotation of the rotor which leads to movement of three protons
PMID:16415858
The a2-isoform is targeted to early endosomes
GO:0006955 immune response
TAS
PMID:2247090
Cloning of a cDNA for a T cell produced molecule with a puta...
MARK AS OVER ANNOTATED
Summary: The old immune-response annotation is not a precise ATP6V0A2 functional annotation. The cited cloning paper reports a putative immune regulatory protein but does not establish the modern V-ATPase a2 mechanism as immune response.
Reason: ATP6V0A2/V-ATPase activity can affect immune-cell and MHC degradation contexts indirectly, but GO:0006955 is too broad and weakly supported by PMID:2247090 for this gene. It should not be considered a core proteostasis annotation.
Supporting Evidence:
PMID:2247090
putative immune regulatory role
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
the in vivo relevance of this observation needs to be confirmed
GO:0007042 lysosomal lumen acidification
NAS
PMID:33065002
Structures of a Complete Human V-ATPase Reveal Mechanisms of...
NEW
Summary: The PN projection proposes lysosomal lumen acidification as a more specific term than existing vacuolar acidification. This is accepted conservatively because ATP6V0A2 is a V0 V-ATPase subunit with lysosomal membrane evidence and broad human V-ATPase evidence for endosome/lysosome pH homeostasis.
Reason: The PN source node is manually mapped to lysosomal lumen acidification and the gene is one of the V0 lysosomal V-ATPase pump components in the projection. Independent literature supports V-ATPase-dependent pH homeostasis of endosomes and lysosomes, and ATP6V0A2 has lysosomal membrane support. The annotation is added as a specific lysosomal acidification term, while broader autophagy/process claims are not promoted.
Supporting Evidence:
file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_annotations.tsv
ATP6V0A2 Autophagy-Lysosome Pathway|Lysosomal catabolism|Regulation of lysosomal environment|Lysosomal acidification|V0 lysosomal v-ATPase proton pump component
PMID:33065002
organellar V-ATPases are essential in establishing and maintaining the pH
PMID:17897319
17 polypeptides comprising or associated with the vacuolar adenosine
file:human/ATP6V0A2/ATP6V0A2-deep-research-manual.md
Both projected terms are accepted conservatively in the review because they are supported by ATP6V0A2 V0-subunit identity, lysosomal membrane evidence, and the broader human V-ATPase endosome/lysosome acidification literature.
GO:0046610 lysosomal proton-transporting V-type ATPase, V0 domain
NAS
PMID:33065002
Structures of a Complete Human V-ATPase Reveal Mechanisms of...
NEW
Summary: The PN projection proposes the lysosomal V0-domain component term. This is accepted because ATP6V0A2 is a V0 a-subunit, GOA already supports V0-domain membership, and lysosomal membrane evidence supports the lysosomal-specific component term.
Reason: The existing GOA captures the broader V0 domain but lacks the lysosomal V0-domain component term. PN mapping and gene-level evidence together support the lysosomal-specific child term without requiring any broader autophagy-process assertion.
Supporting Evidence:
file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_annotations.tsv
GO:0046610 lysosomal proton-transporting V-type ATPase, V0 domain
file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
Subunit of the V0 complex of vacuolar(H+)-ATPase
PMID:17897319
17 polypeptides comprising or associated with the vacuolar adenosine

Core Functions

ATP6V0A2 is a V0-sector a-subunit of the V-ATPase and contributes to ATP-driven proton transmembrane transport that acidifies endosomal, lysosomal, and Golgi compartments. This organelle acidification is the core proteostasis-relevant function, supporting endocytic trafficking, lysosomal degradation, and Golgi pH-dependent glycosylation.

Supporting Evidence:
  • file:human/ATP6V0A2/ATP6V0A2-uniprot.txt
    Subunit of the V0 complex of vacuolar(H+)-ATPase
  • PMID:16415858
    The a2-isoform is targeted to early endosomes
  • PMID:33065002
    V-ATPases are ATP-driven proton pumps comprised of a cytoplasmic V1 complex for ATP hydrolysis and a membrane-embedded Vo complex for proton transfer.
  • file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_annotations.tsv
    ATP6V0A2 Autophagy-Lysosome Pathway|Lysosomal catabolism|Regulation of lysosomal environment|Lysosomal acidification|V0 lysosomal v-ATPase proton pump component

References

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Suggested Questions for Experts

Q: For ATP6V0A2-containing V-ATPase complexes, which cell types and organelles carry the a2 isoform versus other a-subunit isoforms, and should any GO annotations be isoform- or tissue-context restricted?

Q: Does ATP6V0A2 have a direct lysosomal mTORC1 nutrient-sensing role distinct from its general V0-sector contribution to V-ATPase acidification?

Q: Can the ATP6V0A2-ARNO/PSCD2 interaction be represented with a more informative GO molecular-function term than generic protein binding, or should it remain as mechanistic annotation text only?

Suggested Experiments

Experiment: Use endogenous tagging or isoform-specific antibodies to quantify ATP6V0A2 localization across Golgi, early endosome, late endosome, lysosome, plasma membrane, phagosome, and sperm/acrosomal compartments in relevant human cell types.

Hypothesis: ATP6V0A2 has a compartment-biased distribution that explains which lysosomal, Golgi, endosomal, and plasma-membrane GO cellular-component annotations should be core versus context-specific.

Experiment: Measure organelle pH and lysosomal proteolysis after ATP6V0A2-specific knockout or rescue, separating lysosomal lumen acidification from broader vacuolar/endosomal acidification and from other a-subunit compensation.

Hypothesis: ATP6V0A2 makes a measurable gene-specific contribution to lysosomal lumen acidification beyond general V-ATPase family membership.

Experiment: Test whether ATP6V0A2 loss alters mTORC1 recruitment/signaling at lysosomes independently of bulk organelle acidification defects.

Hypothesis: The PN nutrient-sensing placement reflects a V0-sector scaffolding or signaling role that can be experimentally separated from proton transport.

Deep Research

Manual

(ATP6V0A2-deep-research-manual.md)

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πŸ“š Additional Documentation

Notes

(ATP6V0A2-notes.md)

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Pn Notes

(ATP6V0A2-pn-notes.md)

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πŸ“„ View Raw YAML

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