## ATP6V1C2
- **UniProt:** Q8NEY4 · **batch:** proteostasis-batch-2026-06-07 · **review status:** COMPLETE
- **PN placement:** two ALP leaves "V1 lysosomal v-ATPase proton pump component" (Nutrient sensing; Lysosomal acidification). **PN-node mapping:** leaf→GO:0046612 lysosomal V1 domain (more_specific_than_existing_goa); leaf→GO:0033176 V-type ATPase complex (entailed_by_goa_closure); type→GO:0007042 lysosomal lumen acidification (new_to_goa).
- **Consistency:** MOSTLY CONSISTENT. Review/notes describe C2 as a tissue-restricted (kidney/placenta/lung-epithelia) single-copy V1 subunit that is a regulatory hub for reversible V1-V0 assembly/disassembly; required for V1 assembly, contributes to GO:0046961. Crucially, C2 has DIRECT lysosomal-membrane proteomic evidence (PMID:17897319, placental lysosomal membranes — review ACCEPTs GO:0005765 lysosomal membrane). So unlike B1/G3, the lysosomal projection is genuinely supported for C2. PN-projected terms verified real (OLS). No contradiction; PN Notes template ("V1 cytosolic") fits C2.
- **PN story / NEW pressure:** PN asserts lysosomal lumen acidification (flagged new_to_goa) + lysosomal V1 domain. These narrow the review's vacuolar-level/lysosomal-membrane annotations. GO:0007042 is a child of GO:0007035 (not currently in C2's review) but is consistent with the accepted lysosomal-membrane localization. The review did NOT add GO:0007042 or GO:0046612. **ADD GO:0007042 + GO:0046612 — defensible given the lysosomal-membrane IDA-class evidence; verified real.**
- **Mapping strategy:** Gene supports the V1 leaf and (via PMID:17897319) the lysosomal context. Projections are legitimate narrowings, not over-broad. No node-mapping change required; C2 is a positive case for the lysosomal projection.
- **Evidence alignment:** No overlap with PN's generic titles; review better-sourced with C2-specific PMID:12384298 (cloning, tissue-specificity), PMID:17897319 (lysosomal membrane), PMID:20093472 (Wnt/V-ATPase), PMID:21356312 (stalk isoforms). Divergence is review-favorable.
- **Verdict:** CONSISTENT — lysosomal projection supported by direct lysosomal-membrane evidence; PN terms verified real. Optional: add GO:0007042/GO:0046612 to review as narrowings.