InterPro domain: IPR013833
General Information
- Identifier IPR013833
- Description Cytochrome c oxidase, subunit III, 4-helical bundle
- Number of genes 116
- Gene duplication stats Loading...
- Associated GO terms GO:0004129 GO:0022904 GO:0016020
Abstract
Cytochrome c oxidase ( 7.1.1.9 ) 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:
This reaction is coupled to the pumping of four additional protons across the mitochondrial or bacterial membrane [ 1 , 2 ].
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 [ 3 ]. 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.
1. Cytochrome c oxidase: catalytic cycle and mechanisms of proton pumping--a discussion. Biochemistry 38, 15129-40
2. Proton-coupled electron transfer drives the proton pump of cytochrome c oxidase. Nature 440, 829-32
3. Cytochrome oxidase genes from Thermus thermophilus. Nucleotide sequence of the fused gene and analysis of the deduced primary structures for subunits I and III of cytochrome caa3. J. Biol. Chem. 268, 5395-408