Cytochrome C Oxidase Subunit VIII (COX8)

COX8 is the terminal enzyme of the respiratory chain, coupling the transfer of electrons from cytochrome c to molecular oxygen, with the concomitant production of a proton electrochemical gradient across the inner mitochondrial membrane. In addition to 3 mitochondrially encoded subunits, which perform the catalytic function, the eukaryotic enzyme contains nuclear-encoded smaller subunits, ranging in number from 4 in some organisms to 10 in mammals.

It has been proposed that nuclear-encoded subunits may be involved in the modulation of the catalytic function.Since the only COX VIII subunit found in human heart agrees 100% with the polypeptide deduced from this COX8, in distinction to what has been observed in other mammals, only 1 form of COX VIII exists in primates.