## NAA40
- **UniProt:** Q86UY6 · **batch:** proteostasis-batch-2026-06-07c · **review status:** COMPLETE
- **PN placement:** `Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide|NatD, sole component` ; **PN-node mapping:** subtype `NatD, sole component`→no_mapping (correctly suppressed); type→GO:0006474 N-terminal protein amino acid acetylation (ok_for_propagation, new_to_goa)
- **Consistency:** Partial mismatch. The review and notes correctly describe NAA40/NatD as a **monomeric, histone-specific** N-terminal acetyltransferase acting on the N-terminal Ser of **histones H4/H2A in the nucleus/chromatin** (EC 2.3.1.257), explicitly **not** a ribosome-associated nascent-peptide NAT and recognizing substrate independently of the bulk Nt-acetylation machinery. The PN places it under "N-terminal acetylation of **nascent peptide**" — biologically inaccurate for NAA40 (its substrate is mature chromatin histones, not nascent chains). The PN mapping mitigates this by setting the NatD subtype to no_mapping; only the generic type-level BP propagates.
- **PN story / NEW pressure:** PN projects generic BP GO:0006474 (verified real; absent from NAA40 GOA). GO:0006474 is broad enough to technically cover histone N-terminal acetylation, but the review's histone-specific MFs (GO:0010485, GO:0043998, GO:1990189) are far more precise and already capture the biology; a histone-specific N-terminal acetylation **process** term would be preferable to the generic GO:0006474 if added at all. Conclusion: generic GO:0006474 **over-reaches as the framing** (implies nascent-peptide cotranslational role); the specific histone MF/CC content already in the review is the correct capture.
- **Mapping strategy:** The node placement is the concern, not the projected GO per se. NatD does not belong under "nascent peptide husbandry / N-terminal acetylation of nascent peptide" — it is a chromatin/histone modifier. Suppressing the subtype was the right call; consider re-homing NatD to a histone/chromatin PN node, or annotating the type with a histone-specific term rather than the cotranslational-implying generic BP.
- **Evidence alignment:** Mostly concordant. Core anchored to PMID:25619998 (NatD H4/H2A specificity; IDA, VERIFIED). Review flags PMID:25732826 as WRONG_IDENTIFIER (resolves to the Naa60 study, not NAA40) — a genuine citation problem the PN row does not surface. PN row carries no titles.
- **Verdict:** Placement biologically off (histone NAT mis-filed under nascent-peptide husbandry); generic GO:0006474 over-reaches relative to the histone-specific terms already present. **Recommended edits:** Re-home NAA40/NatD from "N-terminal acetylation of nascent peptide" to a histone/chromatin PN node, or replace the projected generic GO:0006474 with a histone-N-terminal-acetylation-specific framing [MAP]; do not add generic GO:0006474 to the review (histone-specific MFs suffice) [YAML]; PMID:25732826 already flagged WRONG_IDENTIFIER — candidate for removal/replacement [REF].