Structure and function of cytochrome bc complexes

The cytochrome be complexes represent a phylogenetically diverse group of c omplexes of electron-transferring membrane proteins, most familiarly repres ented by the mitochondrial and bacterial bc(1) complexes and the chloroplas t and cyanobacterial b(6)f complex. All these complexes couple electron tra nsfer to proton translocation across a closed lipid bilayer membrane, conse rving the free energy released by the oxidation-reduction process in the fo rm of an electrochemical proton gradient across the membrane. Recent exciti ng developments include the application of site-directed mutagenesis to def ine the role of conserved residues, and the emergence over the past five ye ars of X-ray structures for several mitochondrial complexes, and for two im portant domains of the b(6)f complex.