Cocco T, Lorusso M, Sardanelli A M, Minuto M, Ronchi S, Tedeschi G, Papa S
Institute of Medical Biochemistry and Chemistry, University of Bari, Italy.
Eur J Biochem. 1991 Feb 14;195(3):731-4. doi: 10.1111/j.1432-1033.1991.tb15760.x.
Structural and functional characteristics of subunits of bovine heart cytochrome-c reductase have been investigated by controlled digestion of soluble and membrane-reconstituted purified bc1 complex and direct amino acid sequencing of native and digested protein subunits. The results obtained show that the N-terminal segments of core protein II and the 14-kDa protein extend at the periphery of the complex, protruding into the inner matrix space. The Fe-S protein, located at the outer C-periphery of the complex, is shown to be anchored to other subunits of the complex by the amphipathic N-terminal region. Proteolytic cleavage of 7-11 residues from the N-terminal segment of the 14-kDa protein is apparently associated with decoupling of redox-linked proton pumping. Partial digestion of core protein II, the 6.4-kDa protein, and the C-terminal region of the 9.2-kDa protein, is without effect on the redox and proton-motive activity of the complex.
