Electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) in the inner mitochondrial membrane accepts electrons from electron-transfer flavoprotein which is located in the mitochondrial matrix and reduces ubiquinone in the mitochondrial membrane. The two redox centres in the protein, FAD and a [4Fe4S] cluster, are present in a 64-kDa monomer [1].

1: Molecular cloning and expression of a cDNA encoding human electron transfer flavoprotein-ubiquinone oxidoreductase. Goodman SI, Axtell KM, Bindoff LA, Beard SE, Gill RE, Frerman FE; Eur J Biochem 1994;219:277-286. PMID:8306995

2: mucK, a gene in Acinetobacter calcoaceticus ADP1 (BD413), encodes the ability to grow on exogenous cis,cis-muconate as the sole carbon source. Williams PA, Shaw LE; J Bacteriol 1997;179:5935-5942. PMID:9294455