Cytochrome b (MT-CYB)

Component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex) which is part of the mitochondrial respiratory chain. The b-c1 complex mediates electron transfer from ubiquinol to cytochrome c.

Contributes to the creation of a proton gradient across the mitochondrial membrane that's then used for ATP synthesis. .