## HSPA13
- **UniProt:** P48723 (STCH) · **batch:** proteostasis-batch-2026-06-07b · **review status:** COMPLETE
- **PN placement:** one row — `ER proteostasis|Chaperone|HSP70 system|HSP70` (type) ; **PN-node mapping:** HSP70 type → mapped/ok_for_propagation_to_go GO:0140662 ATP-dependent protein folding chaperone (more_specific_than_existing_goa); group/class/branch no_mapping.
- **Consistency:** Notes ↔ review strongly consistent and DIRECTLY contradict the PN mapping. STCH is an atypical HSP70 that carries a ~50-residue ATPase-domain insertion and TRUNCATES the C-terminal substrate/peptide-binding domain; its ATPase is peptide-INDEPENDENT, so it is not a classical foldase (PMID:8131751). Its characterized partners are ubiquilins (UBQLN1/2/4) and SGTA/B, linking it to UPS-associated quality control, not autonomous folding (PMID:10675567). The review MARK_AS_OVER_ANNOTATED on both GOA's GO:0044183 (protein folding chaperone, IBA) and GO:0042026 (protein refolding, IBA) for exactly this reason.
- **PN story / NEW pressure:** PN projects GO:0140662 ATP-dependent protein folding chaperone (verified real; OLS = foldase driven by ATP hydrolysis; child of GO:0044183). The review already rejects the GO:0044183 parent as over-annotation, so projecting the MORE specific foldase child is a sharper over-reach (labeled "more_specific_than_existing_goa" — but more specific in the wrong direction). The evidence-backed MFs are GO:0016887 ATP hydrolysis activity (peptide-independent) and GO:0032182 ubiquitin-like protein binding. This is a clear MS1-flagged atypical-HSP70 case where the PN family label mismaps.
- **Mapping strategy:** This gene should CHANGE the node's behavior: do not propagate GO:0140662 (or GO:0044183) onto P48723. The PN-projected term is narrower-but-wrong (asserts ATP-driven foldase activity the protein cannot perform with a truncated SBD). Per TOMM20/HSPA8/RAB7A precedent, flag HSPA13 as an HSP70-node exception.
- **Evidence alignment:** PN row carries no reference titles; review PMIDs (8131751 STCH ATPase core; 10675567 UbL binding; interactome set) all describe peptide-independent ATPase + ubiquilin/SGT binding — none supports ATP-dependent folding, diverging from the PN projection.
- **Verdict:** Atypical HSP70; PN's GO:0140662 foldase projection is contradicted by the truncated SBD and peptide-independent ATPase — over-reaches. **Recommended edits:** [MAP] do not project GO:0140662 ATP-dependent protein folding chaperone (nor GO:0044183) onto P48723 (PMID:8131751 truncated peptide-binding domain, peptide-independent ATPase); its evidenced MFs are GO:0016887 ATP hydrolysis activity and GO:0032182 ubiquitin-like protein binding.