Essential for mitochondrial respiratory chain complex III (CIII) assembly and stability (PubMed:32161263). Also required for cytochrome c oxidase complex (complex IV) assembly (PubMed:34969438). Interacts with UQCRC1 (PubMed:32161263). Interacts with UQCRQ (By similarity). Interacts with SMIM4 (PubMed:34969438). Cardiac and skeletal muscle (at protein level). Up-regulated in response to glucose, serum, fatty acid starvation and AMPK activation using 5-aminoimidizole-4-carboxamide-1-beta- D-riboside.