Cytochrome b
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| Mitochondrial cytochrome bc1 complex | ||
| Identifiers | ||
|---|---|---|
| Symbol | Cytochrom_B_N | |
| Pfam | PF00033 | |
| InterPro | IPR005797 | |
| PROSITE | PDOC00171 | |
| SCOP | 3bcc | |
| TCDB | 3.D.3 | |
| OPM family | 3 | |
| OPM protein | 1bcc | |
| Available PDB structures:
1bccC:10-205 2e74A:10-205 1l0lC:9-204 1ntkC:9-204 1ntmC:9-204 1ntzC:9-204 1sqqC:9-204 1l0nC:9-204 1sqxC:9-204 1nu1C:9-204 1sqvC:9-204 1sqbC:9-204 1be3C:9-204 1sqpC:9-204 1kb9C:8-205 1p84C:8-205 1kyoC:8-205 1q90B:9-210 1vf5A:9-210 2d2cN:9-210 |
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Cytochrome b/b6 is main subunit of transmembrane cytochrome bc1 and b6f complexes.[1][2] In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.
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[edit] Function
In the mitochondrion of eukaryotes and in aerobic prokaryotes, cytochrome b is a component of respiratory chain complex III (EC 1.10.2.2) - also known as the bc1 complex or ubiquinol-cytochrome c reductase. In plant chloroplasts and cyanobacteria, there is an analogous protein, cytochrome b6, a component of the plastoquinone-plastocyanin reductase (EC 1.10.99.1), also known as the b6f complex. These complexes are involved in electron transport and the generation of ATP and thus play a vital role in the cell.
[edit] Structure
Cytochrome b/b6[3][4] is an integral membrane protein of approximately 400 amino acid residues that probably has 8 transmembrane segments. In plants and cyanobacteria, cytochrome b6 consists of two subunits encoded by the petB and petD genes. Cytochrome b/b6 non-covalently binds two heme groups, known as b562 and b566. Four conserved histidine residues are postulated to be the ligands of the iron atoms of these two heme groups.
[edit] Clinical significance
Mutations in cytochrome b primarily result in exercise intolerance in human patients; though more rare, severe mutli-system pathologies have also been reported.[5]
Single-point mutations in cytochrome b of Plasdmodium falciparum and P. berghei are associated with resistance to the anti-malarial drug atovaquone.[6]
[edit] Human genes
Human genes encoding cytochrome b proteins include:
- CYB5A – cytochrome b5 type A (microsomal)
- CYB5B – cytochrome b5 type B (outer mitochondrial membrane)
- CYBASC3 – cytochrome b, ascorbate dependent 3
- MT-CYB – mitochondrially encoded cytochrome b
[edit] References
- ^ Howell N (August 1989). "Evolutionary conservation of protein regions in the protonmotive cytochrome b and their possible roles in redox catalysis". J. Mol. Evol. 29 (2): 157–69. doi:. PMID 2509716.
- ^ Esposti MD, De Vries S, Crimi M, Ghelli A, Patarnello T, Meyer A (July 1993). "Mitochondrial cytochrome b: evolution and structure of the protein". Biochim. Biophys. Acta 1143 (3): 243–71. doi:. PMID 8329437.
- ^ Howell N (1989). "Evolutionary conservation of protein regions in the protonmotive cytochrome b and their possible roles in redox catalysis". J. Mol. Evol. 29 (2): 157–169. doi:. PMID 2509716.
- ^ Esposti MD, Crimi M, Ghelli A, Patarnello T, Meyer A, De Vries S (1993). "Mitochondrial cytochrome b: evolution and structure of the protein". Biochim. Biophys. Acta 1143 (3): 243–271. doi:. PMID 8329437.
- ^ Blakely EL, Mitchell AL, Fisher N, Meunier B, Nijtmans LG, Schaefer AM, Jackson MJ, Turnbull DM, Taylor RW (July 2005). "A mitochondrial cytochrome b mutation causing severe respiratory chain enzyme deficiency in humans and yeast". FEBS J. 272 (14): 3583–92. doi:. PMID 16008558.
- ^ Siregar JE, Syafruddin D, Matsuoka H, Kita K, Marzuki S (June 2008). "Mutation underlying resistance of Plasmodium berghei to atovaquone in the quinone binding domain 2 (Qo(2)) of the cytochrome b gene". Parasitology International 57 (2): 229–32. doi:. PMID 18248769.
[edit] External links
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