Cytochrome b

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Cytochrome b
Cytochrome b
Ribbon model of cytochrome  bc 1 with cytochrome  b as the largest subunit

Existing structural data : 3BCC , 1L0L

Properties of human protein
Mass / length primary structure 380 amino acids
Cofactor Hamm
Identifier
Gene names MT-CYB (CYB_HUMAN)
External IDs
Occurrence
Parent taxon Creature

Cytochrome b is a group of transmembrane proteins . The representatives are in mitochondria in the respiratory chain in chloroplasts of the photosynthetic or steroid metabolites involved.

properties

Cytochrome b occurs in eukaryotes and aerobic prokaryotes in two protein complexes , in the mitochondrion in the cytochrome bc 1 - (synonym ubiquinol- cytochrome c reductase ) and in chloroplasts in the cytochrome b 6 f complex . Furthermore, cytochrome b5 occurs in proteins used in detoxification and in steroid metabolism , where it catalyzes redox reactions.

Cytochrome b is part of complex III in the respiratory chain and is used to build up the proton motor force , which is then used to synthesize adenosine triphosphate at the ATP synthase . In addition, superoxide is also formed at complex III , which contributes to oxidative stress in a cell .

Cytochrome b and b6 are structurally related. Cytochrome b / b6 is approximately 400 amino acids in length and 8 membrane passages. The cytochrome b6 (in chloroplasts) consists of two subunits, petB and petD . Cytochrome b and b6 each bind two heme groups ( b 562 and b 566 ) as cofactors . Four iron ions are bound by histidines near the heme and thus stabilized on the heme.

Various genes for cytochrome b have been described in humans , including CYB5A in microsomes , CYB5B in the outer mitochondrial membrane, CYBASC3 ( ascorbic acid dependent) and MT-CYB (encoded by mitochondria). Defects in cytochrome b genes lead to, among other things, Liver Optic Atrophy (LHON), Kearns-Sayre syndrome , MELAS syndrome , maternally inherited Leigh syndrome , exercise intolerance or cardiomyopathy . Non-pathological gene variants have been described.

Applications

Cytochrome b is a relatively highly conserved protein, which is why the genes of cytochrome b are used in the course of a DNA analysis to determine the degree of relationship between different species.

Individual evidence

  1. ↑ Homology group at OMA
  2. ↑ MA Schöttler, SZ Tóth, A. Boulouis, S. Kahlau: Photosynthetic complex stoichiometry dynamics in higher plants: biogenesis, function, and turnover of ATP synthase and the cytochrome b 6 f complex. In: Journal of experimental botany. Volume 66, Number 9, May 2015, pp. 2373-2400, doi : 10.1093 / jxb / eru495 , PMID 25540437 .
  3. ↑ KH Storbeck, AC Swart, CL Fox, P. Swart: Cytochrome b5 modulates multiple reactions in steroidogenesis by diverse mechanisms. In: The Journal of steroid biochemistry and molecular biology. Volume 151, July 2015, pp. 66-73, doi : 10.1016 / j.jsbmb.2014.11.024 , PMID 25446886 .
  4. Jump up ↑ P. Lanciano, B. Khalfaoui-Hassani, N. Selamoglu, A. Ghelli, M. Rugolo, F. Daldal: Molecular mechanisms of superoxide production by complex III: a bacterial versus human mitochondrial comparative case study. In: Biochimica et Biophysica Acta . Volume 1827, number 11-12, 2013 Nov-Dec, pp 1332-1339, doi : 10.1016 / j.bbabio.2013.03.009 , PMID 23542447 , PMC 3740082 (free full text).
  5. ↑ C. Breyton: The cytochrome b (6) f complex: structural studies and comparison with the bc (1) complex. In: Biochimica et Biophysica Acta . Volume 1459, Number 2-3, August 2000, pp. 467-474, PMID 11004464 .
  6. ^ S. Saif Hasan, E. Yamashita, WA Cramer: Transmembrane signaling and assembly of the cytochrome b6f-lipidic charge transfer complex. In: Biochimica et Biophysica Acta . Volume 1827, number 11-12, 2013 Nov-Dec, pp. 1295-1308, doi : 10.1016 / j.bbabio.2013.03.002 , PMID 23507619 , PMC 4029431 (free full text).
  7. ^ A b N. Fisher, B. Meunier: Effects of mutations in mitochondrial cytochrome b in yeast and man. Deficiency, Compensation and Disease. In: European Journal of Biochemistry . Volume 268, Number 5, March 2001, pp. 1155-1162, PMID 11231266
  8. ^ J. Castresana: Cytochrome b phylogeny and the taxonomy of great apes and mammals. In: Molecular biology and evolution. Volume 18, Number 4, April 2001, pp. 465-471, PMID 11264397 .
  9. ↑ SN Baharum, AA Nurdalila: Application of 16s rDNA and cytochrome b ribosomal markers in studies of lineage and fish populations structure of aquatic species. In: Molecular biology reports. Volume 39, Number 5, May 2012, pp. 5225-5232, doi : 10.1007 / s11033-011-1320-2 , PMID 22167328 .