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Gene Review

CYTB  -  cytochrome b

Bos taurus

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Disease relevance of CYTB

  • It is proposed that heme is also covalently attached to the cytochrome b subunit of b6f complexes of chloroplasts and cyanobacteria [1].
  • Studies of the cytochrome subunits of menaquinone:cytochrome c reductase (bc complex) of Bacillus subtilis. Evidence for the covalent attachment of heme to the cytochrome b subunit [1].
  • The fumarate reductase system consisting of NADH-coenzyme Q reductase, cytochrome b like component(s) and succinate dehydrogenase/fumarate reductase is thus very important and hence specific inhibitors of the system may prove useful in the effective control of filariasis [2].
  • Whereas all quinolones were efficient inhibitors of electron transport in the cytochrome b/c1-complex from either beef heart or Rhodospirillum rubrum, in complex I from beef heart quinolones 1 and 2 only were highly active [3].
  • In the total cytochrome b content of cytoplasmic membranes from aerobically grown Escherichia coli, four major components are distinguished with alpha-band maxima at 77 K of 555.7, 556.7, 558.6 and 563.5 nm, and midpoint potentials at pH 7.0 of 46, 174, -75 and 187 mV, respectively [4].

High impact information on CYTB

  • On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein [5].
  • We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Qi and/or Qo in the cytochrome b subunit [6].
  • Ilicicolin blocks oxidation-reduction of cytochrome b through center N of the bc(1) complex and promotes oxidant-induced reduction of cytochrome b but has no effect on oxidation of ubiquinol through center P [7].
  • These results have been discussed in relation to the Q-cycle hypothesis and the effect of the redox state of ISP/c(1) on cytochrome b reduction by succinate [8].
  • Ubiquinol:cytochrome c oxidoreductase (complex III). Effect of inhibitors on cytochrome b reduction in submitochondrial particles and the role of ubiquinone in complex III [8].

Biological context of CYTB

  • The fossil record of some ungulate lineages allowed estimation of the evolutionary rates for various components of the cytochrome b DNA and amino acid sequences [9].
  • The result by radioimmunoassay indicated that the content of the iron-sulfur protein/mol of cytochrome b is higher by approximately 30%, on the average, in electron transport particles than in cytochrome bc1 complex [10].
  • It was deduced from these results that the QP center is a spacious pocket formed by domains of cytochrome b, bearing the E-beta-methoxcyacrylate binding site, and the iron-sulfur protein, bearing the stigmatellin binding site [11].
  • Using a mutagenesis approach, we demonstrate that the cytochrome b (QcrB) and c (QcrC) subunits of the complex give rise to bands at 22 and 29 kDa, respectively, after denaturing electrophoresis; that both subunits are required for proper complex assembly and/or stability; and that both subunits retain one heme molecule under denaturing conditions [1].
  • On the other hand, antibodies against bacterial cytochrome b showed significant inhibition of the intact bacterial cytochrome b-c1 complex, indicating that some of the catalytic site epitopes of bacterial cytochrome b are exposed to the hydrophilic environment [12].

Anatomical context of CYTB


Associations of CYTB with chemical compounds

  • (ii) Reverse electron transfer from ISP/c1 to cytochrome b was inhibited more by antimycin than by the P-side inhibitors [17].
  • The granule cytochrome was compared to mitochondrial cytochrome b and, in spite of similar molecular weights and optical spectra, these two proteins were found to be different by the following criteria: 1) amino acid composition, 2) NH2-terminal analysis, 3) interaction with antimycin, and 4) reduction with durohydroquinone [18].
  • The reduction of cytochrome b in the presence of sodium ascorbate was observed on addition of valinomycin to the K(+)-loaded proteoliposomes in a medium containing no external KCl; it was followed by the gradual oxidation [13].
  • The strong up-field chemical shift for TFQ, and lack of significant chemical shift for 9FQ, suggest that the benzoquinone ring is bound near the paramagnetic cytochrome b heme [19].
  • 2) Reverse electron transfer from ISP reduced with ascorbate plus phenazine methosulfate to cytochrome b was studied in SMP, ubiquinone (Q)-depleted SMP containing </=0.06 mol of Q/mol of complex III, and Q-replenished SMP [8].

Other interactions of CYTB

  • The Q0 center is formed by the b-566 domain of cytochrome b, the FeS protein, and maybe an additional small subunit, whereas the Qi center is formed by the b-562 domain of cytochrome b and presumably the 13.4 kDa protein ("QP-C") [15].
  • Complete mitochondrial cytochrome b (1143 bp) and 12S rRNA (956 bp) genes and non-coding regions from the nuclear genes for aromatase cytochrome P-450 (199 bp) and lactoferrin (338 bp) have been compared for 25 bovid species and three Cervidae and Antilocapridae outgroups [20].
  • The gene products studied included: two mitochondrial transcripts, 12S rRNA and cytochrome b mRNA; two RNAs involved in the processing of other RNAs, U2 and U3 snRNA; and two nuclear-derived transcripts, beta-actin mRNA and histone H3 mRNA [21].
  • A molecular phylogeny of the subfamily Antilopinae was determined using the two mitochondrial DNA (mtDNA) genes cytochrome b and cytochrome c oxidase III [22].
  • There are 13 transmembrane helices in each monomer, eight of which belong to cytochrome b, and five of which belong to cytochrome c1, Rieske iron-sulfur protein (ISP), subunits 7, 10 and 11, one each [23].

Analytical, diagnostic and therapeutic context of CYTB


  1. Studies of the cytochrome subunits of menaquinone:cytochrome c reductase (bc complex) of Bacillus subtilis. Evidence for the covalent attachment of heme to the cytochrome b subunit. Yu, J., Le Brun, N.E. J. Biol. Chem. (1998) [Pubmed]
  2. Fumarate reductase system of filarial parasite Setaria digitata. Unnikrishnan, L.S., Raj, R.K. Biochem. Biophys. Res. Commun. (1992) [Pubmed]
  3. Quinolones and their N-oxides as inhibitors of mitochondrial complexes I and III. Reil, E., Höfle, G., Draber, W., Oettmeier, W. Biochim. Biophys. Acta (1997) [Pubmed]
  4. A method for in situ characterization of b- and c-type cytochromes in Escherichia coli and in complex III from beef heart mitochondria by combined spectrum deconvolution and potentiometric analysis. Van Wielink, J.E., Oltmann, L.F., Leeuwerik, F.J., De Hollander, J.A., Stouthamer, A.H. Biochim. Biophys. Acta (1982) [Pubmed]
  5. Crystal structure of the cytochrome bc1 complex from bovine heart mitochondria. Xia, D., Yu, C.A., Kim, H., Xia, J.Z., Kachurin, A.M., Zhang, L., Yu, L., Deisenhofer, J. Science (1997) [Pubmed]
  6. Inhibitor binding changes domain mobility in the iron-sulfur protein of the mitochondrial bc1 complex from bovine heart. Kim, H., Xia, D., Yu, C.A., Xia, J.Z., Kachurin, A.M., Zhang, L., Yu, L., Deisenhofer, J. Proc. Natl. Acad. Sci. U.S.A. (1998) [Pubmed]
  7. Inhibition of the yeast cytochrome bc1 complex by ilicicolin H, a novel inhibitor that acts at the Qn site of the bc1 complex. Gutierrez-Cirlos, E.B., Merbitz-Zahradnik, T., Trumpower, B.L. J. Biol. Chem. (2004) [Pubmed]
  8. Ubiquinol:cytochrome c oxidoreductase (complex III). Effect of inhibitors on cytochrome b reduction in submitochondrial particles and the role of ubiquinone in complex III. Matsuno-Yagi, A., Hatefi, Y. J. Biol. Chem. (2001) [Pubmed]
  9. Evolution of the cytochrome b gene of mammals. Irwin, D.M., Kocher, T.D., Wilson, A.C. J. Mol. Evol. (1991) [Pubmed]
  10. The iron-sulfur protein of cytochrome bc1 complex. Its occurrence in the mitochondrial inner membrane in excess of the amount constituting the complex. Nishikimi, M., Shimomura, Y., Ozawa, T. J. Biol. Chem. (1985) [Pubmed]
  11. Significance of the "Rieske" iron-sulfur protein for formation and function of the ubiquinol-oxidation pocket of mitochondrial cytochrome c reductase (bc1 complex). Brandt, U., Haase, U., Schägger, H., von Jagow, G. J. Biol. Chem. (1991) [Pubmed]
  12. Immunological comparison of the b and c1 cytochromes from bovine heart mitochondria and the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. Haley, P.E., Yu, L., Dong, J.H., Keyser, G.C., Sanborn, M.R., Yu, C.A. J. Biol. Chem. (1986) [Pubmed]
  13. Membrane potential-linked reversed electron transfer in the beef heart cytochrome bc1 complex reconstituted into potassium-loaded phospholipid vesicles. Miki, T., Miki, M., Orii, Y. J. Biol. Chem. (1994) [Pubmed]
  14. The enzymic reduction and kinetics of oxidation of cytochrome b-245 of neutrophils. Cross, A.R., Higson, F.K., Jones, O.T., Harper, A.M., Segal, A.W. Biochem. J. (1982) [Pubmed]
  15. Organization and function of cytochrome b and ubiquinone in the cristae membrane of beef heart mitochondria. von Jagow, G., Link, T.A., Ohnishi, T. J. Bioenerg. Biomembr. (1986) [Pubmed]
  16. Cytochrome b reduction by hexaammineruthenium in mitochondria and submitochondrial particles. Evidence for heme b-562 localization at the M-side of the mitochondrial membrane. Kunz, W.S., Konstantinov, A. FEBS Lett. (1984) [Pubmed]
  17. Ubiquinol:cytochrome c oxidoreductase. Effects of inhibitors on reverse electron transfer from the iron-sulfur protein to cytochrome b. Matsuno-Yagi, A., Hatefi, Y. J. Biol. Chem. (1999) [Pubmed]
  18. Isolation and properties of cytochrome b561 from bovine adrenal chromaffin granules. Duong, L.T., Fleming, P.J. J. Biol. Chem. (1982) [Pubmed]
  19. Protein-ubiquinone interaction in bovine heart mitochondrial succinate-cytochrome c reductase. Synthesis and biological properties of fluorine substituted ubiquinone derivatives. Yang, F., Yu, L., He, D.Y., Yu, C.A. J. Biol. Chem. (1991) [Pubmed]
  20. Evolutionary affinities of the enigmatic saola (Pseudoryx nghetinhensis) in the context of the molecular phylogeny of Bovidae. Hassanin, A., Douzery, E.J. Proc. Biol. Sci. (1999) [Pubmed]
  21. Changes in the relative abundance of various housekeeping gene transcripts in in vitro-produced early bovine embryos. Bilodeau-Goeseels, S., Schultz, G.A. Mol. Reprod. Dev. (1997) [Pubmed]
  22. Phylogenetic relationships in the bovid subfamily Antilopinae based on mitochondrial DNA sequences. Rebholz, W., Harley, E. Mol. Phylogenet. Evol. (1999) [Pubmed]
  23. Structure and reaction mechanisms of multifunctional mitochondrial cytochrome bc1 complex. Yu, C.A., Zhang, L., Deng, K.P., Tian, H., Xia, D., Kim, H., Deisenhofer, J., Yu, L. Biofactors (1999) [Pubmed]
  24. Ubiquinone binding domains in bovine heart mitochondrial cytochrome b. He, D.Y., Yu, L., Yu, C.A. J. Biol. Chem. (1994) [Pubmed]
  25. Application of exciton coupling theory to the structure of mitochondrial cytochrome b. Palmer, G., Degli Esposti, M. Biochemistry (1994) [Pubmed]
  26. Subunit analysis of bovine cytochrome bc1 by reverse-phase HPLC and determination of the subunit molecular masses by electrospray ionization mass spectrometry. Musatov, A., Robinson, N.C. Biochemistry (1994) [Pubmed]
  27. Purification of cytochrome b from complex III of beef heart mitochondria. Nakahara, H., Shimomura, Y., Ozawa, T. Biochem. Biophys. Res. Commun. (1985) [Pubmed]
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