Mitochondrially encoded cytochrome c oxidase subunit 3 (MT-CO3)

Mitochondrially encoded cytochrome c oxidase subunit 3 (MT-CO3) is a 261-amino acid, multi-pass transmembrane protein located in the inner mitochondrial membrane, forming one of the three core subunits of cytochrome c oxidase (complex IV), the terminal enzyme of the mitochondrial respiratory chain. MT-CO3 catalyzes the transfer of electrons from cytochrome c to molecular oxygen, coupled with proton pumping, thereby driving oxidative phosphorylation and ATP production. MT-CO3 is essential for cellular energy metabolism, with mutational defects causing mitochondrial diseases such as LHON, myopathy, and encephalomyopathy. Overexpression has been associated with breast cancer, indicating a possible role in cancer metabolism and a novel, albeit experimental, therapeutic target; preclinical studies have examined interactions with plant-derived compounds. Direct clinical interventions or approved drugs specifically against MT-CO3 are not yet established; targeting the enzyme carries inherent safety risks due to its essential role in normal cellular respiration.

Other names

Cytochrome c oxidase subunit 3COX3COIIICOXIIIMTCO3CO3Cytochrome c oxidase polypeptide IIIhCOX3COX3pP00414

Small molecules or natural compounds may bind to hydrophobic sites and modulate electron transport or oxidative phosphorylation (evidenced by in silico and docking studies, not clinically established); General mechanisms targeting mitochondrial respiration: inhibition of cytochrome c oxidase activity to disrupt ATP production or increase reactive oxygen species.