Homologous Superfamily

Cytochrome c oxidase, subunit III, 4-helical bundle (IPR013833)

Short name: Cyt_c_oxidase_su3_a-hlx

Overlapping entries


Cytochrome c oxidase (EC: is the terminal enzyme of the respiratory chain of mitochondria and many aerobic bacteria. It catalyzes the transfer of electrons from reduced cytochrome c to molecular oxygen:

4 cytochrome c+2 + 4 H+ + O2 --> 4 cytochrome c+3 + 2 H2O

This reaction is coupled to the pumping of four additional protons across the mitochondrial or bacterial membrane [PMID: 10563795, PMID: 16598262].

Cytochrome c oxidase is an oligomeric enzymatic complex that is located in the mitochondrial inner membrane of eukaryotes and in the plasma membrane of aerobic prokaryotes. The core structure of prokaryotic and eukaryotic cytochrome c oxidase contains three common subunits, I, II and III. In prokaryotes, subunits I and III can be fused and a fourth subunit is sometimes found, whereas in eukaryotes there are a variable number of additional small polypeptidic subunits [PMID: 8383670]. The functional role of subunit III is not yet understood.

Subunit III of cytochrome c oxidase has a core structure consisting of 6-7 transmembrane alpha-helices organised into two bundles, one bundle formed by the first two helices and the other by the remaining helices. This entry represents the 4-5 alpha-helical bundle.

GO terms

Biological Process

GO:0022904 respiratory electron transport chain

Molecular Function

GO:0004129 cytochrome-c oxidase activity

Cellular Component

GO:0016020 membrane

Contributing signatures

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