Suppressing expression of the NDUFA11 subunit disrupted Complex I assembly and caused subcomplexes of 550 and 815 kDa to accumulate, providing the stalled intermediates in which assembly factors could be identified.

Eight known extrinsic assembly factors plus a hydrophobic protein, C3orf1 (= TIMMDC1), were associated with those subcomplexes - the observation that first placed TIMMDC1 on Complex I assembly intermediates.

The characteristics of C3orf1 (TIMMDC1), of TMEM126B and of NDUFA11 suggest that all three participate in constructing the membrane arm of Complex I - the basis for the UniProt FUNCTION statement and for the core biological process annotated here.

A systematic map of roughly 14,000 high-quality human binary protein-protein interactions, generated without hypothesis-driven selection; the TIMMDC1 hit it contributes (FATE1) is screen-derived and lacks mitochondrial context.

The study assayed 2,009 missense SNVs across 2,185 protein-protein interactions to measure which coding variants disrupt binding; it is a variant-perturbation screen over an existing interaction set, not a discovery of physiological TIMMDC1 partners.

Roughly 10.5% of the missense variants carried per individual were found to be interaction-disruptive, so the assay's purpose is population-genetic rather than functional characterization of any single protein.

HuRI is a systematic all-by-all yeast two-hybrid screen of about 90% of the protein-coding genome, yielding 52,569 verified binary PPIs among 8,275 proteins; this is the source of the many non-mitochondrial TIMMDC1 partners (SCD, STX6, YIF1A and others).

The authors note that the cellular function of most individual PPIs in the map remains to be elucidated, which is why a HuRI-derived 'protein binding' annotation conveys no molecular function for TIMMDC1.

TMEM70 co-purifies with TIMMDC1 and other MCIA components (ACAD9, NDUFAF1), linking TIMMDC1 to the MCIA complex that supports assembly of the Complex I membrane arm.

BioPlex 3.0 was built by affinity purification of 10,128 human proteins in 293T cells, giving 118,162 interactions among 14,586 proteins; the TIMMDC1-NDUFB11 edge recorded here comes from this network.

The study separates interactions shared across the 293T and HCT116 networks, which reside in core complexes and involve essential proteins, from cell-specific ones that link those complexes. It does not report whether the TIMMDC1-NDUFB11 edge is among the shared set: the edge recorded here comes from BioPlex 3.0, which is the 293T network, so this statistic says nothing about that particular contact. What makes the edge biologically plausible is the identity of the partner - NDUFB11 is a Complex I membrane-arm (ND) subunit - not its recovery across cell lines.

More than 8,000 proteins were classified in mitochondrial preparations of human cells to define MitoCoP, a high-confidence mitochondrial proteome of over 1,100 proteins; TIMMDC1's membership supports its mitochondrial localization by a method orthogonal to the antibody-based HPA call.

The study explicitly reports interactors of respiratory chain and ATP synthase assembly factors, the functional class TIMMDC1 belongs to, but remains an organelle-level inventory that does not resolve submitochondrial compartment.

RNA-seq of patient fibroblasts identified a private exon arising from an intronic cryptic splice site in the Complex I assembly factor TIMMDC1, establishing it as a novel disease-associated gene - a variant class that whole-exome sequencing had missed in both patients.

Re-expression of TIMMDC1 in the patient cells increased Complex I subunit levels, which is what converts the association into causal evidence that TIMMDC1 loss produces the Complex I defect.

The two TIMMDC1 patients presented with muscular hypotonia, developmental delay and neurological deterioration leading to death within the first three years of life, with isolated Complex I deficiency in muscle - the clinical basis for MC1DN31.

The hydrophobic protein (HP) fraction is anchored to the inner mitochondrial membrane by the Intermediate 1 assembly factors NDUFAF3 (C3orf60), NDUFAF4 (C6orf66) and TIMMDC1 (C3orf1) to form Intermediate 2.

The peripheral (flavoprotein) arm subunits join the 815 kDa intermediate to form the 980 kDa complex, a late step of the inner-membrane Complex I biogenesis pathway.

The 315 kDa intermediate - the subcomplex UniProt records TIMMDC1 as associating with - is centred on the core iron-sulfur subunits NDUFS2 and NDUFS3, and the IP subcomplex is anchored to the inner mitochondrial membrane by MT-ND1.

In the final step of Complex I biogenesis the MCIA complex and the assembly factors NDUFAF2-7 and TIMMDC1 dissociate from the 980 kDa complex to leave mature Complex I, confirming that TIMMDC1 is transient and not a holoenzyme subunit.

The distal membrane-arm subunits MT-ND4 and MT-ND5 associate with the 550 kDa complex to form the 815 kDa complex, requiring DMAC1 and DMAC2 - part of the membrane arm whose construction TIMMDC1 supports.

The 315 kDa and 370 kDa subcomplexes associate to form the 550 kDa complex, an intermediate step of the inner-membrane Complex I biogenesis pathway.

Complex I assembly begins with a 315 kDa subcomplex centred on the core iron-sulfur subunits NDUFS2 and NDUFS3; the IP subcomplex then binds NDUFAF3, NDUFAF4 and TIMMDC1 to form Intermediate 1. This is the step in which TIMMDC1 itself acts.