InterPro domain: IPR003213

Cytochrome c oxidase ( 1.9.3.1 ) is an oligomeric enzymatic complex that is a component of the respiratory chain complex and is involved in the transfer of electrons from cytochrome c to oxygen [ 1 ]. In eukaryotes this enzyme complex is located in the mitochondrial inner membrane; in aerobic prokaryotes it is found in the plasma membrane.

In eukaryotes, in addition to the three large subunits, I, II and III, that form the catalytic centre of the enzyme complex, there are a variable number of small polypeptide subunits. One of these subunits is the potentially haem-binding subunit, VIb, which is encoded in the nucleus [ 2 ]. Subunit VIb is one of three mammalian subunits that lacks a transmembrane region. It is located on the cytosolic side of the membrane and helps form the dimer interface with the corresponding subunit on the other monomer complex [ 3 , 4 ].

1. Structure of cytochrome c oxidase. Biochim. Biophys. Acta 726, 135-48
2. Cytochrome oxidase subunit VI of Trypanosoma brucei is imported without a cleaved presequence and is developmentally regulated at both RNA and protein levels. Mol. Microbiol. 39, 272-85
3. Cytochrome c oxidase of mammals contains a testes-specific isoform of subunit VIb--the counterpart to testes-specific cytochrome c? Mol. Reprod. Dev. 66, 8-16
4. Copper deficiency increases fibulin-5 (DANCE/EVEC) but decreases cytochrome C oxidase VIb subunit expression in rat heart. J. Inorg. Biochem. 100, 186-91