InterPro domain: IPR044996

COQ10 is a hydrophobic protein located in the inner membrane of mitochondria that binds coenzyme Q (CoQ), also called ubiquinone, which is an essential electron carrier of the respiratory chain. Deletion of the gene encoding COQ10p (COQ10 or YOL008W) in Saccharomyces cerevisiae results in respiratory defect because of the inability to oxidize NADH and succinate. COQ10 may function in the delivery of CoQ (Q6 in budding yeast) to its proper location for electron transport [ 1 , 2 ]. The human homologue, called Q-binding protein COQ10 homologue A (COQ10A), is able to fully complement for the absence of COQ10 in fission yeast. Human COQ10A also has a splice variant COQ10B [ 3 ].

COQ10 belongs to the SRPBCC (START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC) domain superfamily of proteins that bind hydrophobic ligands. SRPBCC domains have a deep hydrophobic ligand-binding pocket and they bind diverse ligands [ 4 , 5 ].

1. The Saccharomyces cerevisiae COQ10 gene encodes a START domain protein required for function of coenzyme Q in respiration. J Biol Chem 280, 42627-35
2. Coq10, a mitochondrial coenzyme Q binding protein, is required for proper respiration in Schizosaccharomyces pombe. FEBS J. 276, 748-59
3. Human COQ10A and COQ10B are distinct lipid-binding START domain proteins required for coenzyme Q function. J Lipid Res 60, 1293-1310
4. Structure-function analysis of human [corrected] phosphatidylinositol transfer protein alpha bound to phosphatidylinositol. Structure 12, 317-26
5. Structure of human phosphatidylcholine transfer protein in complex with its ligand. Nat. Struct. Biol. 9, 507-11