InterPro : IPR024791

Name  Cytochrome c oxidase subunit III Short Name  Cyt_c/ubiquinol_Oxase_su3
Type  Family Description  Cytochrome c oxidase () is the terminal enzyme of the respiratory chain of mitochondria and many aerobic bacteria. It catalyses the transfer of electrons from reduced cytochrome c to molecular oxygen:4 cytochrome c+2+ 4 H++ O2-->4 cytochrome c+3+ 2 H2OThis reaction is coupled to the pumping of four additional protons across the mitochondrial or bacterial membrane [, ]. 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 []. The functional role of subunit III is not yet understood.As the bacterial respiratory systems are branched, they have a number of distinct terminal oxidases, rather than the single cytochrome c oxidase present in the eukaryotic mitochondrial systems. Although the cytochrome o oxidases do not catalyse the cytochrome c but the quinol (ubiquinol) oxidation they belong to the same haem-copper oxidase superfamily as cytochrome c oxidases. Members of this family share sequence similarities in all three core subunits: subunit I is the most conserved subunit, whereas subunit II is the least conserved [, , ].

Sequence Features

GO Displayer


InterPro protein domain ID --> Contigs



2 Child Features

Id Name Short Name Type
IPR014206 Cytochrome o ubiquinol oxidase, subunit III Cyt_c_ubiqinol_oxidase_su3 Family
IPR014246 Quinol oxidase subunit III QoxC Family

0 Contains

0 Found In

0 Parent Features

6 Publications

First Author Title Year Journal Volume Pages
García-Horsman JA The superfamily of heme-copper respiratory oxidases. 1994 J Bacteriol 176 5587-600
Michel H Cytochrome c oxidase: catalytic cycle and mechanisms of proton pumping--a discussion. 1999 Biochemistry 38 15129-40
Mather MW 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. 1993 J Biol Chem 268 5395-408
Santana M Molecular cloning, sequencing, and physiological characterization of the qox operon from Bacillus subtilis encoding the aa3-600 quinol oxidase. 1992 J Biol Chem 267 10225-31
Chepuri V The sequence of the cyo operon indicates substantial structural similarities between the cytochrome o ubiquinol oxidase of Escherichia coli and the aa3-type family of cytochrome c oxidases. 1990 J Biol Chem 265 11185-92
Belevich I Proton-coupled electron transfer drives the proton pump of cytochrome c oxidase. 2006 Nature 440 829-32

To cite PlanMine, please refer to the following publication:

Rozanski, A., Moon, H., Brandl, H., Martín-Durán, J. M., Grohme, M., Hüttner, K., Bartscherer, K., Henry, I., & Rink, J. C.
PlanMine 3.0—improvements to a mineable resource of flatworm biology and biodiversity
Nucleic Acids Research, gky1070. doi:10.1093/nar/gky1070 (2018)