Cytochrome b (mitochondrially encoded) (MT-CYB)

Cytochrome b (mitochondrially encoded) is a transmembrane protein subunit of complex III—the ubiquinol-cytochrome c reductase complex—within the mitochondrial inner membrane. It mediates electron transfer from ubiquinol to cytochrome c, facilitating the generation of the proton-motive force for ATP synthesis during oxidative phosphorylation. Mutations in MT-CYB disrupt complex III function, leading to mitochondrial deficiencies with varied clinical manifestations, including muscle weakness, exercise intolerance, cardiomyopathy, neurodegenerative disorders, and multisystem disease. MT-CYB is also pharmacologically relevant as a target for drugs that modulate mitochondrial electron transport, with mutation-specific sensitivity to certain therapeutics such as atovaquone and clomipramine.

Other names

Cytochrome bCOBCYTBMTCYBComplex III subunit 3Ubiquinol-cytochrome-c reductase complex cytochrome b subunitCytochrome b-c1 complex subunit 3UQCR3

Inhibition of electron transfer at complex III (e.g., atovaquone and clomipramine bind to ubiquinol or inhibitor sites, impeding electron flow and ATP production)\nModulation of proton gradient, energy production, and redox balance