NDUFA1 (MWFE protein) is a small (70-residue), single-pass membrane accessory ("supernumerary") subunit of mitochondrial respiratory chain Complex I (NADH:ubiquinone oxidoreductase). It is nuclear-encoded on the X chromosome, imported into mitochondria, and is a stable subunit of the membrane arm of the mature holoenzyme, embedded in the inner mitochondrial membrane on the matrix side. It is not one of the 14 conserved catalytic core subunits and carries no redox cofactor, so it is non-catalytic; its role is structural. Despite being non-catalytic, MWFE is absolutely required for assembly and activity of Complex I: loss or truncation of the protein reduces Complex I activity to under 10% and destabilizes co-assembling membrane-arm subunits. Complex I as a whole transfers electrons from NADH to ubiquinone coupled to proton translocation across the inner membrane, feeding the respiratory chain and oxidative phosphorylation. In humans, X-linked loss-of-function variants in NDUFA1 cause mitochondrial complex I deficiency nuclear type 12 (MC1DN12), a mitochondrial encephalomyopathy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0045271 respiratory chain complex I | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) inference that NDUFA1 is part of respiratory chain complex I. This is correct and well supported by direct experimental evidence: NDUFA1/MWFE is a bona fide stable subunit of the Complex I holoenzyme. Core cellular-component annotation. Supporting Evidence: file:human/NDUFA1/NDUFA1-uniprot.txt Complex I is composed of 45 different subunits. |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic annotation to mitochondrial inner membrane. Consistent with the authoritative UniProt subcellular location and with NDUFA1 being an inner-membrane-arm subunit of Complex I. Correct and the most specific membrane location. Supporting Evidence: file:human/NDUFA1/NDUFA1-uniprot.txt Mitochondrion inner membrane |
| GO:1902600 proton transmembrane transport | IEA GO_REF:0000108 | MARK AS OVER ANNOTATED | Summary: Inter-ontology (GO_REF:0000108) inference derived from the NADH dehydrogenase (ubiquinone) activity term (GO:0008137). NDUFA1 does not itself enable GO:0008137 (it is a non-catalytic accessory subunit) and does not itself translocate protons, so this inferred transport annotation is an over-propagation onto an accessory subunit. The complex-level essence (Complex I pumps protons) is not wrong, but attributing proton transport to this subunit over-annotates it. Reason: Automatically inferred from GO:0008137, which itself is a complex-level activity not independently enabled by this non-catalytic accessory subunit. Supporting Evidence: file:human/NDUFA1/NDUFA1-uniprot.txt involved in catalysis. Complex I functions in the transfer of electrons |
| GO:0045271 respiratory chain complex I | IEA GO_REF:0000107 | ACCEPT | Summary: Ensembl-Compara orthology-based electronic transfer of complex membership from mouse ortholog. Correct; redundant with the experimental IDA/IPI and IBA annotations to the same term. Core cellular-component annotation. |
| GO:0005743 mitochondrial inner membrane | IDA PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... | ACCEPT | Summary: Direct-assay (IDA, ComplexPortal) localization to mitochondrial inner membrane, supported by the cryo-EM megacomplex structure in which NDUFA1 is assigned as a Complex I subunit. Correct and consistent with UniProt. Supporting Evidence: file:human/NDUFA1/NDUFA1-uniprot.txt Mitochondrion inner membrane |
| GO:0009060 aerobic respiration | NAS PMID:30030361 Assembly of mammalian oxidative phosphorylation complexes I-... | KEEP AS NON CORE | Summary: Complex/pathway-level biological process attributed by ComplexPortal (NAS). Aerobic respiration is a downstream consequence of Complex I function rather than the direct, subunit-specific function of NDUFA1. Correct as context but broader than this gene's core role; keep as non-core. |
| GO:0042776 proton motive force-driven mitochondrial ATP synthesis | NAS PMID:30030361 Assembly of mammalian oxidative phosphorylation complexes I-... | KEEP AS NON CORE | Summary: Complex/pathway-level process (ComplexPortal NAS). ATP synthesis is a downstream outcome of the proton-motive force generated by the respiratory chain, to which Complex I contributes, but it is not the direct function of this accessory subunit. Keep as non-core contextual annotation. |
| GO:0045271 respiratory chain complex I | IPI PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... | ACCEPT | Summary: Physical-interaction (IPI, ComplexPortal) evidence that NDUFA1 is part of respiratory chain complex I, from the cryo-EM structural assignment of human Complex I subunits. Strong direct evidence for complex membership. Core cellular-component annotation. Supporting Evidence: PMID:28844695 reveals the precise assignment of individual subunits of human CI |
| GO:0005739 mitochondrion | IDA GO_REF:0000052 | KEEP AS NON CORE | Summary: Immunofluorescence-based (HPA, IDA) localization to mitochondrion. Correct but less specific than mitochondrial inner membrane; retained as a valid, if generic, localization. |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | KEEP AS NON CORE | Summary: High-throughput (HTP) detection of NDUFA1 in the high-confidence human mitochondrial proteome. Confirms mitochondrial localization; less specific than the inner-membrane annotations. Keep as supporting, non-core evidence. |
| GO:0045271 respiratory chain complex I | IDA PMID:12611891 The subunit composition of the human NADH dehydrogenase obta... | ACCEPT | Summary: Direct-assay (IDA) identification of NDUFA1 as a subunit of immunopurified human NADH dehydrogenase (Complex I) by mass spectrometry. Primary experimental evidence for complex membership. Core cellular-component annotation. Supporting Evidence: PMID:12611891 we can resolve and identify the human homologues of 42 polypeptides detected so far in the more extensively studied |
| GO:0045271 respiratory chain complex I | IDA PMID:17209039 Identification of mitochondrial complex I assembly intermedi... | ACCEPT | Summary: Direct-assay identification of NDUFA1 as a Complex I subunit in the context of tracing complex I assembly intermediates. Supports both complex membership and the assembly role of this subunit. Core cellular-component annotation. |
| GO:0045271 respiratory chain complex I | IDA PMID:27626371 Accessory subunits are integral for assembly and function of... | ACCEPT | Summary: Direct experimental evidence (gene-editing/knockout plus quantitative proteomics) that NDUFA1 is a strictly required Complex I subunit whose loss destabilizes co-module subunits. Strong support for complex membership and the assembly requirement. Core cellular-component annotation. Supporting Evidence: PMID:27626371 loss of each subunit affects the stability of other subunits residing in the same structural module. |
| GO:0045271 respiratory chain complex I | NAS PMID:9878551 cDNA of eight nuclear encoded subunits of NADH:ubiquinone ox... | ACCEPT | Summary: Non-traceable author statement assigning NDUFA1 to Complex I from the cDNA characterization of nuclear-encoded Complex I subunits. Correct, and corroborated by the multiple IDA/IPI annotations to the same term. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-163217 | ACCEPT | Summary: Traceable-author (Reactome) localization to mitochondrial inner membrane, from the Complex I electron-transfer reaction event. Correct localization for this inner-membrane subunit. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799178 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799179 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799191 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799196 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799197 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-6799202 | ACCEPT | Summary: Reactome TAS inner-membrane localization from a Complex I biogenesis event. Correct localization; redundant with other inner-membrane annotations. |
| GO:0005739 mitochondrion | IDA PMID:16729965 Novel localization of OCTN1, an organic cation/carnitine tra... | KEEP AS NON CORE | Summary: IDA localization to mitochondrion assigned by MGI. The cited paper is primarily about OCTN1 (an organic cation/carnitine transporter) localizing to mitochondria and is not about NDUFA1 function; the mitochondrion localization itself is correct but generic and this reference does not inform NDUFA1's function. Keep as non-core localization support. |
| GO:0006120 mitochondrial electron transport, NADH to ubiquinone | NAS PMID:9878551 cDNA of eight nuclear encoded subunits of NADH:ubiquinone ox... | ACCEPT | Summary: Non-traceable author statement that NDUFA1 is involved in mitochondrial electron transport from NADH to ubiquinone, the defining process of Complex I. This is the core biological process of the complex to which NDUFA1 belongs and is the appropriate BP for this subunit. Supporting Evidence: PMID:9878551 Its main function is the transport of electrons from NADH to ubiquinone, which is accompanied by translocation of protons from the mitochondrial matrix to the intermembrane space. |
| GO:0008137 NADH dehydrogenase (ubiquinone) activity | NAS PMID:9878551 cDNA of eight nuclear encoded subunits of NADH:ubiquinone ox... | MARK AS OVER ANNOTATED | Summary: This is the complex-level catalytic activity of Complex I. NDUFA1/MWFE is a non-catalytic accessory subunit that is not one of the 14 core subunits and carries no redox cofactor, so it does not independently enable NADH dehydrogenase (ubiquinone) activity. A direct `enables` annotation over-annotates this subunit; the correct representation is that NDUFA1 contributes_to this complex-level activity (captured in core_functions) with its own function being structural. Not removed per policy (NAS, essence not entirely wrong at the complex level), but flagged as over-annotated. Reason: GO:0008137 is the activity of the whole Complex I holoenzyme; NDUFA1 is a non-catalytic accessory subunit and does not enable this activity on its own. Supporting Evidence: file:human/NDUFA1/NDUFA1-uniprot.txt involved in catalysis. Complex I functions in the transfer of electrons PMID:10200266 it is not one of the 14 polypeptides making up the core complex I |
| GO:0031966 mitochondrial membrane | IDA PMID:17209039 Identification of mitochondrial complex I assembly intermedi... | KEEP AS NON CORE | Summary: IDA localization to mitochondrial membrane. Correct but less specific than mitochondrial inner membrane, which is separately annotated; retained as a valid, more general localization. |
| GO:0008137 NADH dehydrogenase (ubiquinone) activity | TAS PMID:10200266 The NDUFA1 gene product (MWFE protein) is essential for acti... | MARK AS OVER ANNOTATED | Summary: Traceable-author `enables` of the complex-level NADH dehydrogenase (ubiquinone) activity. The cited paper actually establishes that MWFE/NDUFA1 is a non-catalytic accessory subunit that is essential for Complex I activity, not that it is itself catalytic. As with the NAS annotation to the same term, a direct `enables` over-annotates this accessory subunit; it contributes_to the activity rather than enabling it. Flagged as over-annotated (not removed; experimental/TAS support and essence at the complex level). Reason: NDUFA1 is essential for Complex I activity but is a non-catalytic accessory subunit; it contributes to rather than independently enables GO:0008137. Supporting Evidence: PMID:10200266 the MWFE polypeptide is absolutely essential for an active complex I in mammals. PMID:10200266 it is not one of the 14 polypeptides making up the core complex I |
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