Source of the single PANTHER phylogenetically-inferred (IBA) annotation for NDUFA13, propagating respiratory chain complex I membership (GO:0045271, part_of) from characterised orthologues of the GRIM-19/NDUFA13 accessory subunit family. The mitochondrion and mitochondrial inner membrane localizations come from other sources (GO_REF:0000120, GO_REF:0000052 and the experimental references), not from this IBA.

Basis for exactly one NDUFA13 annotation - located_in GO:0005634 nucleus (IEA) - produced by mapping the UniProtKB Q9P0J0 Nucleus subcellular location statement (UniProtKB-SubCell:SL-0191) to GO. It is a vocabulary mapping of an existing UniProt statement rather than independent evidence, and it duplicates the EXP nucleus annotation from PMID:12628925. The mitochondrial inner membrane IEA comes from GO_REF:0000120, not from this reference.

Basis for GO annotations curated from immunofluorescence imaging. For NDUFA13 this supports a predominantly mitochondrial staining pattern; imaging alone cannot resolve the inner-membrane sub-compartment or distinguish the minor nuclear pool reported in the GRIM-19 literature.

Basis for annotations produced by combining multiple automated IEA pipelines; these add no independent experimental evidence for NDUFA13 beyond what the sequence-based and orthology-based methods already assert.

GRIM-19 (NDUFA13) was discovered in an antisense knock-out screen as a gene required for interferon-beta plus retinoic acid-induced tumour cell death.

Antisense knock-down of GRIM-19 confers resistance to IFN/RA-induced death and overexpression enhances it, establishing the pro-death moonlighting role.

The discovery paper reported GRIM-19 as primarily nuclear and IFN/RA-inducible; later work localised the bulk of the protein to mitochondria, so this nuclear assignment should be read as a minor pool.

NDUFA13/GRIM-19 was identified by mass spectrometry among the polypeptides of immunopurified human Complex I, primary evidence for Complex I membership.

An independent yeast two-hybrid screen identified GRIM-19 as a STAT3-specific interactor that does not bind STAT1 or STAT5a.

GRIM-19 represses STAT3 transcriptional activity and target gene expression and suppresses growth of STAT3-driven cells.

GRIM-19 co-localises with mitochondrial markers, and sequestration of STAT3 with GRIM-19 blocks EGF-stimulated STAT3 nuclear translocation.

GRIM-19 binds STAT3 and inhibits STAT3-driven transcription without blocking STAT3 activation or DNA binding, defining a transcriptional co-repressor mode of action rather than a kinase/phosphatase activity.

The STAT3 transactivation domain, particularly Ser727, is required for GRIM-19 binding, and GRIM-19 does not bind other STATs - establishing specificity.

OLFM4/GW112 associates with GRIM-19 and attenuates GRIM-19-mediated IFN-beta/retinoic acid apoptosis, a regulatory input onto the GRIM-19 cell-death function.

Germline deletion of GRIM-19 in mice is lethal at embryonic day 9.5 and produces abnormal mitochondrial structure and distribution.

GRIM-19 is present in native mitochondrial Complex I and its primary localisation is mitochondrial, not nuclear.

Loss of GRIM-19 destroys Complex I assembly and electron transfer activity, the primary evidence for its core structural/assembly role.

GRIM-19 interacts with endogenous NOD2 and is required for NF-kappaB activation downstream of muramyl dipeptide sensing, a non-core innate-immunity role.

GRIM-19 is required for NOD2-dependent NF-kappaB activation and restricts pathogen invasion of intestinal epithelial cells.

siRNA knockdown of GRIM-19 (and NDUFS3) confers resistance to IFN-beta/RA-induced apoptosis and reduces ROS, linking Complex I subunit function to the cell-death response.

Complex I assembles stepwise via discrete subcomplexes, demonstrated here by tracing tagged NDUFS3. The cached record does not mention NDUFA13/GRIM-19, so this paper establishes the stepwise-assembly framework only; NDUFA13's entry with the hydrophobic-fraction intermediate is taken from Reactome R-HSA-6799178, which names NDUFA13 explicitly.

A yeast two-hybrid screen identified the mitochondrial serine protease HtrA2 as a GRIM-19 binding partner, and the interaction promotes IFN/RA-dependent cell death.

In the presence of GRIM-19, HtrA2-driven destruction of XIAP is enhanced - the basis for the protease-activator and positive-regulation-of-protein-catabolism annotations.

Large-scale huntingtin-interactor screen combining yeast two-hybrid and affinity pull-down; an NDUFA13 hit here is a high-throughput dataset entry rather than evidence for a specific molecular function.

GRIM-19 acts as a chaperone that recruits STAT3 into mitochondria, a specific and unusual function for a Complex I accessory subunit.

GRIM-19 additionally promotes integration of STAT3 into Complex I, and this requires STAT3 Ser727.

The first germline pathogenic NDUFA13 mutation was identified in two sisters with early-onset hypotonia, dyskinesia and optic neuropathy, establishing NDUFA13 as a Complex I deficiency disease gene.

Patient cells show a selective Complex I enzymatic defect with complexes II, III and IV largely spared, indicating a Complex I-specific requirement for NDUFA13.

Loss of NDUFA13 protein drastically reduces Complex I holoenzyme and supercomplex levels, and silencing NDUFA13 in control cells reproduces this - direct evidence for a stability/assembly role.

Systematic CRISPR knockout of each human Complex I accessory subunit showed most, including NDUFA13, are strictly required for assembly of a functional complex.

The 14 core subunits shared with bacteria carry catalysis; the 31 human accessory subunits including NDUFA13 are non-catalytic, supporting a structural rather than enzymatic molecular function.

Loss of one accessory subunit destabilises other subunits of the same structural module, the proteomic signature underlying the assembly role.

Cryo-EM of the human respiratory megacomplex assigned individual Complex I subunits, placing NDUFA13 within Complex I in a higher-order supercomplex.

Complex I is present in two copies within a circular megacomplex with dimeric complex III and two copies of complex IV.

Review establishing that OXPHOS supernumerary subunits such as NDUFA13 act in assembly, regulation and stability rather than in catalysis.

Complexes I, III and IV associate into respiratory supercomplexes, the higher-order context relevant to the complex-level respiration annotations.

BioID proximity-labelling map of mitochondrial intermembrane space proteases; an NDUFA13-HTRA2 proximity hit here is consistent with the characterised GRIM-19/HtrA2 association but is a high-throughput dataset entry, not a molecular function.

Large-scale yeast two-hybrid interactome centred on neurodegeneration-associated proteins; the NDUFA13 entry is an untargeted screen hit (source of a bare HTT protein-binding IPI) with no NDUFA13- or complex I-specific functional follow-up, so it supports no molecular function for this gene.

NDUFA13 is a member of the stringently defined human mitochondrial high-confidence proteome (MitoCoP), corroborating mitochondrial localization at coarse resolution.

Multimodal (biophysical interaction plus immunofluorescence) map of human subcellular assemblies in U2OS cells; NDUFA13 entries derived from it are assembly-membership data points rather than evidence for a distinct molecular function.

Reactome reaction describing the catalytic output of Complex I - NADH oxidation with ubiquinone reduction coupled to proton pumping. NDUFA13 contributes as a structural subunit of the complex catalysing this reaction, not as a catalytic component.

Reactome assembly step in which the hydrophobic protein (HP) fraction containing NDUFA13 joins Intermediate 1, direct pathway support for the mitochondrial respiratory chain complex I assembly annotation.

Late assembly step adding flavoprotein (FP) peripheral-arm subunits; NDUFA13 is not among the subunits added here, having entered with the HP fraction earlier.

Assembly step forming the 315 kDa subcomplex around the NDUFS2/NDUFS3 core; downstream of this, the NDUFA13-containing HP fraction is incorporated.

Final step of Complex I biogenesis in which assembly factors dissociate to leave the mature holoenzyme containing NDUFA13.

Distal membrane-arm assembly step in which MT-ND4 and MT-ND5 are integrated; NDUFA13 is not directly involved in this step.

Assembly step joining the 315 kDa and 370 kDa subcomplexes to form the 550 kDa intermediate en route to the mature complex containing NDUFA13.

Reactome reaction stating that NDUFA13 binds HTRA2 in the mitochondrion and allosterically activates its protease activity, the pathway representation of the endopeptidase-activator function; the interaction is enhanced by interferon-beta and retinoic acid.

Reactome reaction in which activated HTRA2 cleaves NDUFA13 at six sites; NDUFA13 is the substrate here, and Reactome explicitly notes that the consequence of this cleavage for apoptosis is unclear.