NDUFAF1 (CIA30 / Q9Y375) — review notes

Identity and family

• NDUFAF1 = CIA30 = "Complex I intermediate-associated protein 30, mitochondrial"; alt name "NADH dehydrogenase [ubiquinone] 1 alpha subcomplex assembly factor 1" [file:human/NDUFAF1/NDUFAF1-uniprot.txt "RecName: Full=Complex I intermediate-associated protein 30, mitochondrial"].
• Belongs to the CIA30 family; has a cleavable N-terminal mitochondrial transit peptide (residues 1–24) and a galactose-binding domain-like fold (Pfam PF08547 CIA30) [file:human/NDUFAF1/NDUFAF1-uniprot.txt "Belongs to the CIA30 family"], [file:human/NDUFAF1/NDUFAF1-uniprot.txt "TRANSIT 1..24"].
• Human homologue of the Neurospora crassa complex I chaperone CIA30 PMID:16218961.

Function (assembly factor, NOT a catalytic/structural subunit)

• Function per UniProt: "As part of the MCIA complex, involved in the assembly of the mitochondrial complex I" [file:human/NDUFAF1/NDUFAF1-uniprot.txt "As part of the MCIA complex, involved in the assembly of the"].
• Required for CI assembly: RNAi knockdown reduces amount and activity of complex I PMID:16218961; NDUFAF1 associates with 600/700 kDa assembly intermediates PMID:16218961.
• Acts early: CIA30 "associates with newly translated mtDNA-encoded complex I subunits at early stages in their assembly before dissociating at a later stage" PMID:17557076, and is "a crucial component in the early assembly of complex I" PMID:17557076.
• Assembly factors dissociate from the mature holoenzyme (Reactome: "The MCIA complex ... dissociate from the 980kDa complex, resulting in Complex I"). => NDUFAF1 has NO role in electron transport itself; GO:0006120 (NADH->ubiquinone electron transport) is an over-annotation.

MCIA complex membership (GO:0160295)

• MCIA core subunits: NDUFAF1, ECSIT, ACAD9, TMEM126B; plus TMEM186 and COA1 PMID:32320651, [file:human/NDUFAF1/NDUFAF1-uniprot.txt "comprises at least the core subunits TMEM126B, NDUFAF1, ECSIT and ACAD9"].
• Architecture: ECSIT bridges the complex — NDUFAF1 binds ECSIT's N-terminal domain, ACAD9 binds ECSIT's C-terminal domain; NDUFAF1 does NOT bind ACAD9 directly PMID:33320993, PMID:34646991.
• Purified mature NDUFAF1 (25–327) is a monodisperse monomer PMID:33320993.
• ACAD9/ECSIT/NDUFAF1 ternary complex is soluble and stable PMID:34646991.

Interactions

• ECSIT PMID:17344420; ACAD9 PMID:20816094; TMEM70/TMEM242 (via MCIA) PMID:33753518.
• HuRI (PMID:32296183) binary-interactome hits (PNLIPRP1, SLC30A2, STX8, TMEM86B, TMEM97, YIPF6) are not known MCIA partners. The IPI rows still assert observed binary interactions and have no contradictory evidence, so they are retained as non-core; GO:0005515 remains mechanistically uninformative.

Localization

• Mitochondrion; mitochondrion matrix; peripherally associated with the matrix face of the inner membrane [file:human/NDUFAF1/NDUFAF1-uniprot.txt "Peripherally associated with the matrix face of the mitochondrial inner membrane"].

Disease

• Biallelic NDUFAF1 mutations cause mitochondrial complex I deficiency nuclear type 11 (MC1DN11), a cardioencephalomyopathy / fatal infantile hypertrophic cardiomyopathy [file:human/NDUFAF1/NDUFAF1-uniprot.txt "Mitochondrial complex I deficiency, nuclear type 11 (MC1DN11)"], PMID:17557076.

Review decisions summary

• Core BP: GO:0032981 mitochondrial respiratory chain complex I assembly (ACCEPT, well supported IDA/IMP/IBA/NAS).
• Core CC: GO:0160295 mitochondrial complex I intermediate assembly complex (ACCEPT, multiple IDA).
• Core MF: none assigned. Live QuickGO now marks GO:0051082 obsolete, but more importantly the NDUFAF1 evidence does not establish direct recognition of an unfolded protein, carrier-specific holdase activity, or autonomous refolding. The phrase “assembly chaperone” and association with newly translated complex-I subunits PMID:17557076 describe an assembly role, not an assayed molecular function. Neither GO:0044183 nor GO:0140309 is therefore an evidence-matched replacement. The local cache/ontologies/go.tsv snapshot dated 2026-03-21 is stale: it still records label unfolded protein binding and False for obsoletion. Live ontology status and the durable Unfolded Protein Binding project status take precedence. No NADH dehydrogenase / oxidoreductase catalytic MF was assigned.
• GO:0006120 (electron transport NADH->ubiquinone, NAS) => MARK_AS_OVER_ANNOTATED (assembly factor, not a CI subunit).
• GO:0065003 (protein-containing complex assembly, NAS) => MODIFY to GO:0032981 (too general).
• All five exact "protein binding" GO:0005515 IPI signatures => KEEP_AS_NON_CORE: each retains a physical-interaction assertion without converting heterogeneous partners into a single mechanism; MCIA membership is represented more informatively by GO:0160295.
• Mitochondrion GO:0005739 (general) localizations => KEEP_AS_NON_CORE; matrix (GO:0005759) => ACCEPT; inner membrane (GO:0005743) => KEEP_AS_NON_CORE (peripheral).

2026-08-28 qualifier-aware re-review

• Current GOA contains 36 physical rows collapsing to 27 exact qualifier-aware signatures: 14 enables, 6 involved_in, 1 is_active_in, 12 located_in, and 3 part_of physical rows. Every exact signature is represented once in the YAML; repeated WITH/FROM partners for a signature were not duplicated.
• Final actions across the 27 current GOA signatures: 8 ACCEPT, 17 KEEP_AS_NON_CORE, 1 MARK_AS_OVER_ANNOTATED, and 1 MODIFY; 0 REMOVE and 0 UNDECIDED. Separately, the legacy UniProt IBA:GO_Central GO:0051082 propagated claim is retained machine-readably as MARK_AS_OVER_ANNOTATED, giving 28 reviewed claims total (8 ACCEPT, 17 KEEP_AS_NON_CORE, 2 MARK_AS_OVER_ANNOTATED, 1 MODIFY).
• PAINT provenance was fetched through just fetch-panther-paint PTHR13194 --extra-uniprot Q9Y375; the retained interpro/panther/PTHR13194/PTHR13194-paint.tsv contains exactly two IBD rows. NDUFAF1 is in PANTHER family PTHR13194, subfamily PTHR13194:SF23 (“COMPLEX I INTERMEDIATE-ASSOCIATED PROTEIN 30, MITOCHONDRIAL”). Both current IBAs descend from PTN000324265: GO:0005739 is seeded by FB:FBgn0039689 and human Q9Y375; GO:0032981 is seeded by FB:FBgn0039689, WB:WBGene00008225, and Q9Y375. The target's appearance among the sources is expected and experimentally grounded by its direct localization and assembly evidence, not circularity. GO:0051082 is absent from this current PAINT slice and from current GOA; its separate review records the stale UniProt cross-reference rather than inventing a current PTN provenance.
• Abstract-only restraint was applied to PMIDs 11935339, 16218961, 17344420, 17557076, 20816094, and 32320651. Their experimental GO annotations were retained because the cached abstracts affirm the relevant localization, assembly, and interaction claims; no assay detail beyond the cached text was invented.
• The core synthesis is process/complex/location based: NDUFAF1 is a non-catalytic MCIA assembly factor for the ND2 module PMID:32320651. GO:0006120 remains over-annotated because early assembly support does not make NDUFAF1 part of the mature electron-transfer reaction.