CYTOCHROME B(5), ITS FUNCTIONS, STRUCTURE AND MEMBRANE TOPOLOGY [Review]

摘要

The first part of the present communication reviews recent advances in our understanding of the known physiological functions of cytochrome b(5). In addition, one section is devoted to a description of a recently discovered function of cytochrome b(5), namely its involvement in the synthesis of the oncofetal antigen N-glycolylneuraminic acid. The second part of the article summarizes site-directed mutagenesis studies, primarily conducted in the author's laboratory in both the catalytic heme-binding and membrane-binding domain of cytochrome b(5). These studies have shown that: 1) the membrane binding domain of cytochrome b(5) spans the bilayer; 2) cytochrome b(5) lacking 19 COOH-terminal amino acids does not bind to membrane bilayers; and 3) specific amino acids in the membrane binding domain have been mutated and shown not to be essential for the function of cytochrome b(5) with its redox partners. [References: 130]