Cytochrome c oxidase subunit IV family (IPR004203)

Short name: Cyt_c_oxidase_su4_fam

Overlapping homologous superfamilies

Family relationships


Cytochrome c oxidase (CcO)(EC:, the terminal oxidase in the respiratory chains of eukaryotes and most bacteria, is a multi-chain transmembrane protein located in the inner membrane of mitochondria and the cell membrane of prokaryotes. It catalyzes the reduction of O2 and simultaneously pumps protons across the membrane. The number of subunits varies from three to five in bacteria and up to 13 in mammalian mitochondria. Subunits I, II, and III of mammalian CcO are encoded within the mitochondrial genome and the remaining 10 subunits are encoded within the nuclear genome. Found only in eukaryotes, subunit IV is the largest of the nuclear-encoded subunits. It binds ATP at the matrix side, leading to an allosteric inhibition of enzyme activity at high intramitochondrial ATP/ADP ratios. In mammals, subunit IV has a lung-specific isoform and a ubiquitously expressed isoform [PMID: 11311561, PMID: 16336199, PMID: 12973739, PMID: 12270909, PMID: 12909344, PMID: 11035249, PMID: 9752724, PMID: 8638158, PMID: 16760263, PMID: 16631971, PMID: 16199211, PMID: 15598510].

This family is composed of cytochrome c oxidase subunit 4 [PMID: 11311561], and subunits 5A and 5B [PMID: 2824989]. Proteins in this entry also include the yeast COX IV subunit, Mtc3 (maintenance of telomere cappining 3) protein [PMID: 18845848, PMID: 14562095].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004129 cytochrome-c oxidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.