Falcon deep research report for ATP6V1G3
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Among the three human G-subunit isoforms, G3 is kidney-enriched, G1 is ubiquitous, and G2 is brain-specific - corroborating the kidney-restricted expression of G3 and supporting the KEEP_AS_NON_CORE treatment of the neuronal/synaptic-vesicle IBA annotations transferred across the G family.
"**G3 is the kidney-specific/enriched G-subunit isoform**; by contrast **G1 is ubiquitous** and **G2 is brain-specific**"
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The report explicitly states that direct experimental literature on human ATP6V1G3 is very limited and that most functional/localization/signaling claims (cancer, mTORC1, Wnt/Notch, endolysosomal trafficking, RILP/RAB7) are inferred from the V-ATPase holoenzyme or other G isoforms (notably the G1-specific RILP/RAB7 study), not directly demonstrated for G3. These inferred, complex/family-level claims are therefore NOT attributed to G3 in this review.
"Very limited direct experimental literature on human ATP6V1G3"
Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Electronic Gene Ontology annotations created by ARBA machine learning models
Combined Automated Annotation using Multiple IEA Methods
V1 and V0 domains of the human H+-ATPase are linked by an interaction between the G and a subunits.
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G3 subunit expression is limited to the kidney among major organs of mouse and man, with additional expression in human inner-ear epithelium; G3 assembles with other kidney-specific subunits (a4, C2, d2) plus B1 into a tissue-specific proton pump.
"in major organs of both mouse and man, G3 subunit expression is limited to the kidney"
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G3 directly binds the V0 a4 subunit (pulled down from kidney membranes by immobilized full-length G3), confirming a4 and G3 are subunits of the same pump and providing a V1-V0 link required for assembly and regulation; similar G1/a1, G3/a1, and G1/a4 interactions occur.
"purified, immobilized full-length G3 to pull down the a4 subunit from human kidney membrane preparations"
Molecular cloning and characterization of novel tissue-specific isoforms of the human vacuolar H(+)-ATPase C, G and d subunits, and their evaluation in autosomal recessive distal renal tubular acidosis.
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ATP6V1G3 (G3) is a kidney-specific isoform of the V-ATPase G subunit, identified and characterized alongside tissue-specific C and d subunit isoforms.
"novel tissue-specific isoforms of the human vacuolar H(+)-ATPase C, G and d subunits"
UniProt entry Q96LB4 (VATG3_HUMAN), V-type proton ATPase subunit G 3
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G3 is a subunit of the V1 peripheral complex of the V-ATPase; the V1 complex includes three peripheral stalks each formed by an E-G heterodimer.
"three peripheral stalks each consisting of EG heterodimers"
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The V-ATPase acidifies intracellular compartments and, in some cell types, is targeted to the plasma membrane to acidify the extracellular environment.
"is targeted to the plasma membrane, where it is responsible for acidifying the extracellular environment"
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ATP6V1G3 tissue specificity is kidney.
"TISSUE SPECIFICITY: Kidney."
Intraphagosomal pH is lowered to 5 by V-ATPase
Acidification of Tf:TfR1 containing endosome
RRAGC,D exchanges GTP for GDP
RRAGA,B exchanges GDP for GTP
v-ATPase:Ragulator:RRAGA,B:GTP:RRAGC,D:GDP:SLC38A9:Arginine dissociates yielding v-ATPase:Ragulator:RRAGA,B:GTP:RRAGC,D:GDP and SLC38A9:Arginine
v-ATPase:Ragulator:RagA,B:GDP:RagC,D:GDP binds SLC38A9:Arginine
v-ATPase:Ragulator:RRAGA,B:GTP:RRAGC,D:GDP binds mTORC1