Cytochrome c oxidase subunit II-like, transmembrane region superfamily

This entry represents the transmembrane region from subunit II of the membrane protein cytochrome C oxidase. This includes subunit II from mitochondrial [14673090], bacterial aa3-type [9380672] and bacterial ba3-type [10775261] cytotochrome c oxidases, as well as subunit II of cytochrome O ubiquinol oxidase [11017202].

Cytochrome c oxidase [6307356, 8083153] 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 ), 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.