Cytochrome b Information & Cytochrome b Links at HealthHaven.com

	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

Cytochrome b/b6 is the 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.

[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 multi-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:10.1007/BF02100114. 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:10.1016/0005-2728(93)90197-N. 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:10.1007/BF02100114. 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:10.1016/0005-2728(93)90197-N. 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:10.1111/j.1742-4658.2005.04779.x. 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:10.1016/j.parint.2007.12.002. PMID 18248769.

[edit] External links

MeSH Cytochromes+b

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[pmid2509716-0] 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:10.1007/BF02100114. PMID 2509716.

[pmid8329437-1] 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:10.1016/0005-2728(93)90197-N. PMID 8329437.

[PUB00003404-2] 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:10.1007/BF02100114. PMID 2509716.

[PUB00000640-3] 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:10.1016/0005-2728(93)90197-N. PMID 8329437.

[pmid16008558-4] 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:10.1111/j.1742-4658.2005.04779.x. PMID 16008558.

[pmid18248769-5] 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:10.1016/j.parint.2007.12.002. PMID 18248769.

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