## HYPK
- **UniProt:** Q9NX55 · **batch:** proteostasis-batch-2026-06-07c · **review status:** COMPLETE
- **PN placement:** TWO rows. Row 1 (TR) `Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide|Modulator of NatA and NatE complexes` (type `N-terminal acetylation`=mapped→GO:0006474 N-terminal protein amino acid acetylation [new_to_goa]; subtype/group=no_mapping; class/branch=context_only). Row 2 (UPS) `Ubiquitin and UBL binding|other protein modifiers|N-terminal acetylation|UBA (NACA)` — all no_mapping; class=context_only→GO:0140036 ubiquitin-modified protein reader activity.
- **Consistency:** Mostly consistent, with one tension. Deep research and review agree HYPK is an intrinsically disordered NatA-associated chaperone that (a) suppresses polyQ-HTT aggregation (GO:0044183 protein folding chaperone, EXP/IDA) and (b) is a non-catalytic NatA subunit that INHIBITS NatA N-terminal acetyltransferase activity (core_function GO:0010699 acetyltransferase inhibitor activity). The PN row-1 projection of GO:0006474 (N-terminal acetylation, the catalytic process) sits awkwardly: HYPK does not itself acetylate and the review explicitly frames HYPK as a NatA inhibitor/modulator. So PN's "performs N-terminal acetylation" projection partially contradicts the review's "inhibits/modulates NatA" reading.
- **PN story / NEW pressure:** PN row 1 → GO:0006474 N-terminal protein amino acid acetylation (verified real). This is NOT in HYPK's GOA, but HYPK is a regulatory/modulator subunit, not a catalytic acetyltransferase — projecting the catalytic process term over-attributes activity. The review's own GO:0010699 acetyltransferase inhibitor activity (MF) and complex membership (GO:0031415 NatA complex) better capture the role. Row 2 (UPS / NACA-domain reader) is correctly no_mapping. Conclusion: **over-reaches** — GO:0006474 should not be propagated to HYPK as an enabling/involved_in catalytic term.
- **Mapping strategy:** Recommend the type-node GO:0006474 be treated as context_only for HYPK (it is a regulator, not a catalyst). The review correctly does not annotate HYPK with N-terminal acetyltransferase activity. UPS-branch no_mappings are appropriate (NatA/UBA-domain reader context, no single safe GO assertion).
- **Evidence alignment:** PN row 1 lists no titles; row 2 lists signature domain IPR044034 (UBA/NAC domain), no PMIDs. Review anchors on PMID:17947297 (chaperone/anti-apoptosis), PMID:18076027 (intrinsically disordered chaperone), PMID:20154145 (HYPK-NatA complex, cotranslational NAT + anti-HTT-aggregation). No citation conflict.
- **Verdict:** Mostly consistent; PN's catalytic N-terminal-acetylation projection over-reaches for a NatA-modulator. **Recommended edits:** treat node GO:0006474 as context-only for HYPK (do not propagate the catalytic process term); keep the review's GO:0010699 inhibitor activity + GO:0031415 NatA complex as the accurate captures [MAP].