Yeast mitochondrial respiratory chain complex III (Complex III)

Yeast mitochondrial respiratory chain complex III, commonly referred to as the cytochrome bc1 complex or ubiquinol-cytochrome c reductase, is a multi-subunit enzyme complex located in the inner mitochondrial membrane of Saccharomyces cerevisiae and related species. It catalyzes the transfer of electrons from ubiquinol (coenzyme Q) to cytochrome c, a process coupled to the translocation of protons from the mitochondrial matrix to the intermembrane space, thus contributing to the proton motive force required for ATP synthesis. Complex III typically functions as a homodimer and forms supramolecular assemblies (supercomplexes) with other respiratory complexes, particularly complex IV, further optimizing electron flow and energy conversion. Its proper assembly and function require several core and accessory subunits, as well as specific assembly factors.[1][2][3][7] Inhibitors targeting complex III are used experimentally to probe mitochondrial function and can lead to severe bioenergetic defects. Mutations or defects in complex III or its assembly factors result in compromised cellular respiration and growth phenotypes in yeast, and by extension, similar pathologies in human disease.[1][2][6]

Other names

Cytochrome bc1 complexUbiquinol-cytochrome c reductasebc1 complex

Inhibition of electron transfer from ubiquinol to cytochrome c, disrupting proton gradient formation and ATP synthesis