InterPro domain: IPR036257

Cytochrome c oxidase ( 1.9.3.1 ) [ 1 , 2 ] is an oligomeric enzymatic complex which is a component of the respiratory chain and is involved in the transfer of electrons from cytochrome c to oxygen. In eukaryotes this enzyme complex is located in the mitochondrial inner membrane; in aerobic prokaryotes it is found in the plasma membrane. The enzyme complex consists of 3-4 subunits (prokaryotes) to up to 13 polypeptides (mammals).

Subunit 2 (CO II) transfers the electrons from cytochrome c to the catalytic subunit 1. It contains two adjacent transmembrane regions in its N terminus and the major part of the protein is exposed to the periplasmic or to the mitochondrial intermembrane space, respectively. CO II provides the substrate-binding site and contains a copper centre called Cu(A) (see IPR001505 ), probably the primary acceptor in cytochrome c oxidase. An exception is the corresponding subunit of the cbb3-type oxidase which lacks the copper A redox-centre. Several bacterial CO II have a C-terminal extension that contains a covalently bound haem c.

The N-terminal domain of cytochrome C oxidase contains two transmembrane alpha-helices [ 3 ].

1. Structure of cytochrome c oxidase. Biochim. Biophys. Acta 726, 135-48
2. The superfamily of heme-copper respiratory oxidases. J. Bacteriol. 176, 5587-600
3. The whole structure of the 13-subunit oxidized cytochrome c oxidase at 2.8 A. Science 272, 1136-44