Examples demonstrating target disambiguation, evidence grading, and biological model synthesis.
"What does the literature say about ATP6V1A?"
Agent: I'll conduct comprehensive research on ATP6V1A. A few questions:
1. **Scope**: Comprehensive overview, or specific focus (druggability, disease, mechanism)?
2. **Known aliases**: Any specific names you use for this target?
3. **Methods appendix**: Do you want search methodology in a separate file?
User: Comprehensive. I know it's part of V-ATPase. No methods file needed.
1.1 Resolve Identifiers
## Target Identity
| Identifier | Value | Source |
|------------|-------|--------|
| Official Symbol | ATP6V1A | HGNC via UniProt |
| UniProt | P38606 | UniProt_search |
| Ensembl Gene | ENSG00000114573 | UniProt_id_mapping |
| NCBI Gene ID | 523 | MyGene_get_gene_annotation |
| ChEMBL Target | CHEMBL2364682 | OpenTargets |
**Full Name**: V-type proton ATPase catalytic subunit A
**Synonyms**: ATP6A1, VPP2, Vma1, VA68, V-ATPase A subunit1.2 Collision Check
Search: "ATP6V1A"[Title] - first 20 results reviewed.
### Naming Collision Assessment
**Collision risk**: LOW
- Symbol "ATP6V1A" is unambiguous
- Related but distinct: ATP6V0A1-4 (V0 domain vs V1 domain)
- "V-ATPase" is a complex name that may include V0 subunits
**Search strategy**:
- Use exact symbol for precision: "ATP6V1A"
- For broader V-ATPase context: "V-ATPase" AND (V1 OR catalytic OR "A subunit")
- Exclude pure V0 papers when V1-specific: NOT "V0 domain" NOT "a1 subunit"1.3 Protein Architecture
### Protein Architecture
| Domain | Position | InterPro ID | Function |
|--------|----------|-------------|----------|
| V-ATPase A, N-terminal | 1-90 | IPR022879 | ATP binding regulatory |
| V-ATPase A, catalytic | 91-490 | IPR005725 | Catalytic activity |
| V-ATPase A, C-terminal | 491-617 | IPR022878 | V1 complex assembly |
**Length**: 617 aa (canonical isoform)
**Isoforms**: 2
- P38606-1 (canonical): 617 aa
- P38606-2: Missing 1-45, 572 aa
**Key Sites**:
- Lys-168: ATP binding (active site)
- Glu-261: Catalytic glutamate
*Sources: InterPro, UniProt*1.4 Expression Profile
### Baseline Tissue Expression (GTEx v8)
| Tissue | TPM | Rank | Interpretation |
|--------|-----|------|----------------|
| Kidney - Cortex | 145.3 | 1 | Elevated |
| Liver | 98.7 | 2 | Medium-high |
| Brain - Cerebellum | 87.2 | 3 | Medium |
| Lung | 76.4 | 4 | Medium |
| Ubiquitous baseline | ~50 | - | Broad |
**Tissue Specificity**: Low (τ = 0.28) - broadly expressed housekeeping gene
**Implication**: Essential cellular function; targeting may have broad effects
*Source: GTEx_get_median_gene_expression*1.5 Functional Annotations
### GO Annotations
**Molecular Function**:
- Proton-transporting ATPase activity, rotational mechanism (GO:0046961) [IDA]
- ATP binding (GO:0005524) [IDA]
- ATP hydrolysis activity (GO:0016887) [IDA]
**Biological Process**:
- Lysosomal acidification (GO:0007041) [IMP]
- Autophagy (GO:0006914) [IMP]
- pH regulation (GO:0006885) [IBA]
- Bone resorption (GO:0045453) [IMP]
**Cellular Component**:
- Vacuolar proton-transporting V-type ATPase, V1 domain (GO:0000221) [IDA]
- Lysosomal membrane (GO:0005765) [IDA]
*Source: GO_get_annotations_for_gene, OpenTargets*Query Strategy Applied:
- High-precision:
"ATP6V1A"[Title]→ 23 papers (core set) - Citation expansion from top 15 → 89 additional papers
- Collision-filtered broad:
"V-ATPase" AND (V1 OR "A subunit") AND (mechanism OR acidification)→ 156 papers
Deduplication: 268 raw → 187 unique papers
## 6. Core Mechanisms
### 6.1 Molecular Function
ATP6V1A is the catalytic A subunit of the vacuolar H+-ATPase (V-ATPase),
responsible for ATP hydrolysis that drives proton translocation across membranes
[★★★ Mechanistic: PMID:12345678, crystal structure + biochemistry].
The V1 sector containing ATP6V1A performs ATP hydrolysis, while the V0
sector mediates proton transport. Rotation of the central stalk couples
ATP hydrolysis to proton pumping [★★★: PMID:23456789, cryo-EM structure].
**Evidence Quality**: Strong (8 mechanistic studies with direct biochemical evidence)
### 6.2 Biological Role
**Lysosomal Acidification**
V-ATPase acidifies lysosomes to pH 4.5-5.0, required for:
- Acid hydrolase activity [★★★: PMID:34567890]
- Autophagosome-lysosome fusion [★★☆: PMID:45678901, knockdown phenotype]
- Protein degradation [★★☆: PMID:56789012]
**mTORC1 Signaling**
ATP6V1A participates in lysosomal amino acid sensing:
- V-ATPase interacts with Ragulator complex [★★★: PMID:67890123]
- Required for mTORC1 recruitment to lysosome [★★☆: PMID:78901234]
- Bafilomycin A1 inhibits mTORC1 via V-ATPase [★★★: PMID:89012345]
**Bone Resorption**
Osteoclasts use V-ATPase for extracellular acidification:
- ATP6V1A mutation causes osteopetrosis [★★★: PMID:90123456, patient genetics + functional]
- Osteoclast-specific V-ATPase inhibitors in development [★★☆: PMID:01234567]
**Evidence Quality**: Strong (lysosome), Moderate (mTORC1), Strong (bone)## 12. Research Themes
### 12.1 Lysosomal Function & Autophagy (47 papers)
**Evidence Quality**: Strong (32 mechanistic, 11 functional, 4 association)
ATP6V1A is essential for lysosomal acidification, which is prerequisite for
autophagy completion. Studies demonstrate that:
- V-ATPase activity required for autophagosome-lysosome fusion [★★★: PMID:xxx]
- Bafilomycin A1 blocks autophagic flux via V-ATPase inhibition [★★★: PMID:xxx]
- ATP6V1A knockdown accumulates LC3-II and p62 [★★☆: PMID:xxx]
**Representative papers** (≥3 required):
1. Forgac M (2007) - V-ATPase structure-function review [★★★: PMID:17428758]
2. Zoncu R et al (2011) - mTORC1 senses amino acids via V-ATPase [★★★: PMID:22153073]
3. Settembre C et al (2013) - TFEB controls lysosomal biogenesis [★★★: PMID:23332759]
4. Abu-Remaileh M et al (2017) - Lysosomal metabolomics [★★★: PMID:28893638]
5. [Additional papers...]
### 12.2 Cancer & Tumor Acidification (28 papers)
**Evidence Quality**: Moderate (8 functional, 15 association, 5 review)
V-ATPase contributes to tumor microenvironment acidification:
- Upregulated in metastatic cancers [★☆☆: PMID:xxx, expression correlation]
- V-ATPase inhibitors show anti-cancer effects [★★☆: PMID:xxx, xenograft study]
- Acidic pH promotes invasion and metastasis [★★☆: PMID:xxx]
**Representative papers**:
1. Neri D & Supuran CT (2011) - Tumor pH and V-ATPase [PMID:21677680]
2. [Additional papers...]
### 12.3 Bone Biology & Osteopetrosis (19 papers)
**Evidence Quality**: Strong (genetic + functional studies)
[Content with evidence grades...]
### 12.4 Viral Infection (12 papers)
**Evidence Quality**: Moderate
Multiple viruses exploit V-ATPase for entry:
- Influenza virus requires acidic endosomes [★★★: PMID:xxx]
- SARS-CoV-2 entry blocked by V-ATPase inhibitors [★★☆: PMID:xxx]
- Flavivirus membrane fusion pH-dependent [★★☆: PMID:xxx]
### 12.5 Neurodegenerative Disease (8 papers)
**Evidence Quality**: Limited (mostly association)
[Content with evidence grades...]
### 12.6 Assays & Tools (15 papers)
**Evidence Quality**: Methodological
[Assay development papers...]## 14. Biological Model & Testable Hypotheses
### 14.1 Integrated Biological Model
ATP6V1A is the catalytic engine of the V-ATPase proton pump, essential for
acidifying lysosomes and other intracellular compartments. Our literature
synthesis supports the following model:
**Core Function**: ATP6V1A hydrolyzes ATP to power proton translocation,
maintaining lysosomal pH at 4.5-5.0 [strong evidence from 15+ mechanistic studies].
**Regulatory Hub**: V-ATPase acts as a signaling hub, connecting nutrient
status to mTORC1 via the Ragulator-Rag pathway. When amino acids are present,
V-ATPase promotes mTORC1 lysosomal recruitment [moderate evidence, mechanism
still debated].
**Disease Relevance**:
- Loss-of-function: Osteopetrosis (osteoclast defect), neurodegeneration
(impaired autophagy) [strong genetic evidence]
- Gain-of-function/upregulation: Cancer progression, tumor acidification
[moderate association evidence]
- Exploitation: Viral entry dependency [strong for influenza, moderate for others]
**Key Uncertainty**: The precise mechanism of V-ATPase-mTORC1 coupling,
specifically whether V-ATPase ATPase activity vs. scaffolding function
is required, remains debated [conflicting evidence from 4 studies].
### 14.2 Testable Hypotheses
| # | Hypothesis | Perturbation | Readout | Expected | Priority |
|---|------------|--------------|---------|----------|----------|
| 1 | ATP6V1A is required for autophagy completion | siRNA knockdown in HeLa | LC3-II levels, p62 accumulation, GFP-LC3 puncta | ↑LC3-II, ↑p62, puncta accumulation | HIGH |
| 2 | V-ATPase ATPase activity (not just presence) is required for mTORC1 signaling | Concanamycin A treatment vs knockdown | pS6K levels, mTOR localization | Both reduce pS6K; knockdown more severe if scaffolding matters | HIGH |
| 3 | ATP6V1A inhibition blocks SARS-CoV-2 entry | Bafilomycin A1 pretreatment | Viral RNA, spike protein, infection | ↓ infection in dose-dependent manner | MEDIUM |
| 4 | ATP6V1A expression correlates with cancer metastasis | TCGA pan-cancer analysis | Survival, metastasis-free survival | High ATP6V1A → worse prognosis in epithelial cancers | MEDIUM |
| 5 | V-ATPase inhibitor synergizes with autophagy inducers in cancer | Combination of bafilomycin + rapamycin | Cell death, xenograft growth | Synergistic cytotoxicity | MEDIUM |
### 14.3 Suggested Experiments
**For Hypothesis 1 (Autophagy)**:
- siRNA targeting ATP6V1A in HeLa or MEFs
- Treat ± bafilomycin A1 as positive control
- Western blot for LC3-II, p62
- Confocal microscopy for GFP-LC3 puncta
- Electron microscopy for autophagosome accumulation
- Expected: Knockdown phenocopies bafilomycin
**For Hypothesis 2 (mTORC1 mechanism)**:
- Compare: (a) Concanamycin A (inhibits activity), (b) ATP6V1A siRNA (removes protein)
- Readouts: pS6K, p4E-BP1, mTOR lysosomal localization (IF)
- Include rescue with catalytically-dead ATP6V1A mutant
- Expected: If scaffolding sufficient, siRNA more severe than inhibitor### Naming Collision Assessment
**HIGH COLLISION RISK DETECTED**
Search `"TRAG"[Title]` reveals multiple meanings:
1. **T-cell regulatory gene (human TRAF1)** - Immune signaling
2. **Bacterial TraG** - Conjugation/plasmid transfer protein
3. **TraG-like domain** - Bioinformatics/structural studies
**Resolution**:
- User clarification needed: "Is this T-cell TRAG or bacterial TraG?"
- If T-cell: Use TRAF1 as primary symbol
- Apply filter: NOT plasmid NOT conjugation NOT "TraG domain"### Resolved Query Strategy
**Target**: TRAF1 (also known as TRAG, EBI6)
**Collision filter**: NOT plasmid NOT conjugation NOT bacterial NOT "type IV secretion"
**High-precision queries**:
1. "TRAF1"[Title] AND (immune OR T-cell OR NF-kB)
2. "TRAF1" AND lymphoma
3. "TRAG" AND T-cell NOT plasmid NOT conjugation
**Citation expansion**: From TRAF1 signaling papers, expand citations"GPRC5D"[Title] → Only 8 papers
"GPRC5D" broader → 23 papers total
### Citation Network Strategy Applied
**Seed papers** (8 core papers from title search):
- PMID:31919438 - GPRC5D as multiple myeloma target
- PMID:33020169 - CAR-T targeting GPRC5D
- [6 more]
**Forward citations** from seeds:
- PubMed_get_cited_by → 67 additional papers
- EuropePMC_get_citations → 12 unique (not in PubMed)
**Backward citations** from seeds:
- EuropePMC_get_references → 45 additional (mostly myeloma biology)
**Final corpus**: 132 papers (from 8 initial)
**Note**: For this sparse target, citation expansion (124 papers) vastly
outperformed keyword search (23 papers)."ATP6V1A is involved in autophagy and cancer."
**Autophagy**:
ATP6V1A is essential for lysosomal acidification, which is required for
autophagy completion [★★★ Mechanistic: PMID:22153073, biochemical + genetic].
Knockdown in cell lines causes LC3-II accumulation [★★☆ Functional: PMID:28893638].
Multiple reviews discuss V-ATPase-autophagy connection [★☆☆ Mention: PMIDs:xxx,yyy].
**Cancer**:
ATP6V1A is upregulated in several cancers [★☆☆ Association: TCGA data, PMID:xxx].
V-ATPase inhibitors show anti-proliferative effects in xenografts [★★☆ Functional:
PMID:yyy]. The mechanistic role in cancer progression is hypothesized but not
directly demonstrated [no ★★★ mechanistic studies identified].
**Summary**:
- Autophagy link: STRONG evidence (mechanistic studies)
- Cancer link: MODERATE evidence (functional + association, no mechanistic){
"metadata": {
"generated": "2026-02-04T15:30:00Z",
"query": "ATP6V1A",
"target_identifiers": {
"symbol": "ATP6V1A",
"uniprot": "P38606",
"ensembl": "ENSG00000114573"
},
"total_raw": 268,
"total_unique": 187,
"collision_filter_applied": false
},
"papers": [
{
"pmid": "22153073",
"doi": "10.1126/science.1207056",
"title": "mTORC1 senses lysosomal amino acids through an inside-out mechanism that requires the vacuolar H+-ATPase",
"authors": ["Zoncu R", "Bar-Peled L", "Efeyan A", "Wang S", "Sancak Y", "Sabatini DM"],
"year": 2011,
"journal": "Science",
"source_databases": ["PubMed", "OpenAlex", "Crossref"],
"evidence_tier": "T1",
"evidence_tier_rationale": "Mechanistic study with biochemistry and genetics",
"themes": ["mtorc1_signaling", "lysosomal_function"],
"is_core_seed": true,
"citation_count": 1847,
"oa_status": "bronze",
"oa_url": null
},
{
"pmid": "28893638",
"doi": "10.1126/science.aan6298",
"title": "Lysosomal metabolomics reveals V-ATPase- and mTOR-dependent regulation of amino acid efflux from lysosomes",
"authors": ["Abu-Remaileh M", "Wyant GA", "Kim C", "Laqtom NN", "Abbasi M", "Chan SH", "Freinkman E", "Sabatini DM"],
"year": 2017,
"journal": "Science",
"source_databases": ["PubMed", "EuropePMC"],
"evidence_tier": "T1",
"themes": ["lysosomal_function", "metabolism"],
"is_core_seed": true,
"citation_count": 612,
"oa_status": "gold",
"oa_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5704954/"
}
],
"theme_summary": {
"lysosomal_function": {"count": 47, "evidence_quality": "strong"},
"cancer": {"count": 28, "evidence_quality": "moderate"},
"bone_biology": {"count": 19, "evidence_quality": "strong"},
"viral_infection": {"count": 12, "evidence_quality": "moderate"},
"neurodegenerative": {"count": 8, "evidence_quality": "limited"},
"methodology": {"count": 15, "evidence_quality": "methodological"}
}
}- Disambiguation first - Resolve IDs, check collisions before searching
- Evidence grading everywhere - T1-T4 labels on all claims
- Citation-first for sparse targets - Expand from seeds when keywords fail
- Collision-aware queries - Apply NOT filters for ambiguous names
- Mandatory sections - Include all 15 sections, even if "limited evidence"
- Biological model - Synthesize evidence into testable hypotheses
- Scalable bibliography - Narrative in report, full data in JSON