Structural and Functional Features of the Eleven Constituent Proteins of the Mammalian Ubiquinol: Cytochrome c Reductase
Beef heart ubiquinol:cytochrome c reductase (the reductase) consists of 11 subunits, three catalytic and eight non-catalytic ones. The primary structures of all subunits except the two core proteins have been determined. The three catalytic subunits contain the four redox centres, i.e., three hemes and one iron-sulfur cluster, while the function of the remaining eight non-catalytic subunits has not been clearly established so far. The folding patterns derived from the amino acid sequence data indicate that all six small subunits are integral membrane proteins or anchored in the membrane. The reductase seems to be a multi-subunit complex held together predominantly by ionic bonds. The ‘core’ of the reductase is a four α-helical antiparallel bundle formed by the transmembrane helices II-V of cytochrome b, incorporating the two b-heme centres in a transmembrane arrangement.
KeywordsSmall Subunit Neurospora Crassa Folding Pattern Beef Heart Amphipathic Helix
Unable to display preview. Download preview PDF.
- 1.Wakabayashi, S., Matsubara, H., Kim, C.H., Kawai, K., and King, T.E. (1982) J. Biochem. 91, 2077–2085Google Scholar
- 9.Wakabayashi, S., Takeda, H., Matsubara, H., Kim, C.H., and King, T.E. (1982) J. Biochem. 91, 2077–2085Google Scholar
- 10.Wakabayashi, S., Takao, T., Shimonishi, Y., Kuramitsu, S., Matsubara, W., Wang, T., Zhang, Z., and King, T.E. (1985) J. Biol. Chem. 260, 337–343Google Scholar
- 11.Schägger, H., Von Jagow, G., Borchart, U., and Machleidt, W. (1983) Hoppe-Seyler‘s Z. Physiol. Chem. 364, 307–311Google Scholar
- 15.Yu, L., Yang, F.D. and Yu, C.A. (1985) J. Biol. Chem. 260, 963–973Google Scholar
- 17.Link, T.A., Schägger, H., and Von Jagow, G. (1986a) Fourth European Bioenergetics Conference (EBEC). Short Reports, p. 166Google Scholar
- 18.Ohnishi, T. and Von Jagow, G. (1985) Biophys. J.47, 241a.Google Scholar