Complex III assembly

Assembly of the cytochrome c (cytochrome bc1) reductase (Complex III) was mainly investigated in yeast. The process in humans is considered to recapitulate the process in the yeast system based on the high similarity in structure and composition of the yeast and human complexes. Human Complex III probably consists of two identical sub-complexes, each containing at least 11 subunits: the catalytic core containing cytochrome b (MT-CYTB), cytochrome c1 (CYC1), and the Rieske protein (UQCRFS1), as well as the additional subunits UQCRC1, UQCRC2, UQCRC10, UQCRC11, UQCRCB, UQCRCH, UQCRCQ (Guo et al., 2017; Dennerlein et al., 2021; reviewed in Ndi et al., 2018; Signes & Fernandez-Vizarra, 2018). While complex I, III, and IV form a supercomplex, there is no evidence of any physiological advantage of this configuration (reviewed in Kohler et al., 2023; Brischigliaro et al., 2023).

Summary from Reactome (R-HSA-9865881), read 2026-09-23.