Cytochrome c oxidase (COX) is the terminal complex (complex IV) of the electron transfer chain, embedded in the mitochondrial inner membrane. It catalyzes electron transfer from reduced cytochrome c to molecular oxygen in a process coupled to the transfer of protons across the inner membrane, thus contributing to the generation of the proton gradient that is used by ATP synthase to drive ATP synthesis. Eukaryotic COX is a multimeric enzyme formed by subunits of dual genetic origin. The three subunits forming the catalytic core of the enzyme (COX1, COX2 and COX3) are encoded by the mitochondrial DNA. (Adapted from
PMID:17091399 and
PMID:28870773.)
