
Structure of the cytochrome c oxidase complex of rat liver
Author(s) -
JARAUSCH Jochen,
KADENBACH Bernhard
Publication year - 1985
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1985.tb08641.x
Subject(s) - cytochrome c oxidase , biochemistry , cytochrome c , electron transport complex iv , chemistry , cytochrome , microbiology and biotechnology , enzyme , mitochondrion , biology
The orientation of the thirteen polypeptides of rat‐liver cytochrome c oxidase in the inner mitochondrial membrane was studied by proteolytic digestion of mitoplasts and sonicated particles. After separation by sodium dodecylsulfate gel electrophoresis proteins were transferred on nitrocellulose, and individual polypeptides were identified by incubation with polypeptide‐specific antisera, followed by fluorescein‐isothiocyanate‐conjugated protein A. The three catalytic polypeptides I–III and seven nuclear coded polypeptides (IV, Vb, VIa, VIc, VIIa, VIIb and VIII) were found accessible to proteases from the cytoplasmic phase. Polypeptides II, IV, Va, Vb and VIa were accessible from the matrix phase, indicating a transmembraneous orientation of polypeptides II, IV, Vb and VIa. Together with data on cross‐linking and on cytochrome‐ c ‐protected labeling of polypeptides, a model of the cytochrome c oxidase complex was developed. It is suggested that the cytochrome c binding site on polypeptide II is surrounded by several nuclear‐coded polypeptides, which may modulate the affinity of the enzyme towards cytochrome c .