NDUFA1

UniProt ID: O15239
Organism: Homo sapiens
Review Status: INITIALIZED
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Gene Description

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.

Existing Annotations Review

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

Core Functions

Structural accessory subunit of the membrane arm of mitochondrial respiratory chain Complex I; non-catalytic itself but required for assembly and activity, contributing to the complex's NADH:ubiquinone oxidoreductase activity as part of mitochondrial electron transport from NADH to ubiquinone.

Supporting Evidence:
  • file:human/NDUFA1/NDUFA1-uniprot.txt
    Accessory subunit of the mitochondrial membrane respiratory
  • PMID:10200266
    the MWFE polypeptide is absolutely essential for an active complex I in mammals.
  • PMID:27626371
    We show that 25 subunits are strictly required for assembly of a functional complex

References

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Notes

(NDUFA1-notes.md)

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