Mitochondrial cytochrome bc1 complex (Complex III)

Mitochondrial cytochrome bc1 complex (Complex III) is a multi-subunit enzyme embedded in the inner mitochondrial membrane. It serves as a central component of the electron transport chain by transferring electrons from ubiquinol (reduced coenzyme Q) to cytochrome c while simultaneously pumping protons across the membrane. This process contributes to the electrochemical gradient that drives ATP synthesis via oxidative phosphorylation. The core catalytic subunits include cytochromes b and c1 and an iron-sulfur protein. The activity of Complex III is essential for efficient energy production in eukaryotic cells, but it also generates reactive oxygen species as a byproduct, which can contribute both to physiological signaling and pathological damage if dysregulated. Dysfunction or inhibition of this complex impairs cellular respiration and has been implicated in various diseases including inherited mitochondrial disorders, neurodegeneration, cardiovascular conditions, cancer metabolism alterations, and fibrotic diseases[1][3][5][7].

Other names

Cytochrome bc1 complexCoenzyme Q-cytochrome c reductaseUbiquinol-cytochrome c oxidoreductaseRespiratory chain complex III

Inhibition of electron transfer, leading to disruption of ATP production and increased ROS formation[3]