Cytochrome b subunit (Cytochrome b)

Cytochrome b subunit is an integral membrane protein that is the key component of the cytochrome bc1 complex (Complex III) in the mitochondrial electron transport chain of eukaryotes and in the corresponding complexes of prokaryotes and photosynthetic organisms[2][8][1]. It contains eight transmembrane helices and coordinates two non-covalently bound heme groups crucial for electron transfer[1][2][3]. The cytochrome b subunit couples the transfer of electrons from ubiquinol to cytochrome c with proton translocation across the mitochondrial membrane, helping generate the proton gradient necessary for ATP production[2][6][8]. Inhibitors of the cytochrome b subunit disrupt cellular ATP synthesis and are therapeutically important as antimicrobials or antifungals (e.g., atovaquone, azoxystrobin)[2][5]. Mutations in its gene are linked to mitochondrial diseases and also serve as markers for drug resistance in pathogens. The structure and function of cytochrome b are highly conserved, though the chloroplast homolog (cytochrome b6) participates in the photosynthetic electron transport chain[1][4].

Other names

Cytochrome bCytochrome b-c1 complex subunit 1Cytochrome bc1 complex cytochrome b subunitubiquinol-cytochrome c reductase cytochrome b subunitmitochondrial cytochrome bcytochrome b6 (chloroplast homolog)

Inhibition of electron transfer in the bc1 complex; Disruption of proton motive force and ATP generation; Induction of oxidative stress by impaired electron flow