title: Studies on cytochrome c oxidase, XII. Isolation and primary structure of polypeptide VIb from bovine heart.
abstract: The isolation and complete sequence analysis of the cytoplasmically synthesized polypeptide VIb from bovine heart cytochrome c oxidase is described. The protein is a stoichiometric constituent of the respiratory complex IV. Its primary structure is deduced from N-terminal sequencing and overlapping peptides obtained from tryptic cleavage and specific cleavage at arginyl and tryptophyl peptide bonds. The polypeptide chain consists of 84 amino acids from which a Mr of 9419 is derived. It has a relatively high content of histidine and proline and contains a single cysteine. A hydrophobic sequence of 20 amino acids points to a membrane-penetrating structure similar to that found in polypeptides I, II, III, IV and VIIIa, VIIIb, VIIIc of the bovine oxidase. The sequence of VIb is tissue-specific, it contributes to the formation of nuclear coded isoenzymes of cytochrome c oxidase. The protein thus may be involved in a tissue-specific regulation of cellular respiration.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003576:Electron Transport Complex IV / Q000032:analysis* / Q000302:isolation & purification; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology; D010455:Peptides / Q000302:isolation & purification
chemical_list: D010455:Peptides; D003576:Electron Transport Complex IV