Cytochrome b

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 protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary

Cytochrome B C-terminal domain
cytochrome bc1 complex from chicken
Identifiers
Symbol	Cytochrom_B_C
Pfam	PF00032
InterPro	IPR005798
PROSITE	PDOC00171
SCOP	1bcc
TCDB	3.D.3
Available protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary

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.

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.

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.

Use in phylogenetics

Cytochrome b is commonly used to determine phylogenetic relationships between organisms due to its sequence variability. It is considered to be most useful in determining relationships within families and genera. Comparative studies involving cytochrome b have resulted in new classification schemes and have been used to assign newly described species to a genus, as well as deepen the understanding of evolutionary relationships.^[5]

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.^[6]

Single-point mutations in cytochrome b of Plasdmodium falciparum and P. berghei are associated with resistance to the anti-malarial drug atovaquone.^[7]

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

References

1. ^ 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. 
2. ^ 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. 
3. ^ 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. 
4. ^ 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. 
5. ^ Castresana, J. (2001). "Cytochrome b Phylogeny and the Taxonomy of Great Apes and Mammals". Molecular Biology and Evolution 18 (4): 465–471. PMID 11264397. http://mbe.oxfordjournals.org/cgi/reprint/18/4/465. 
6. ^ 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. 
7. ^ 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. 

External links

• MeSH Cytochromes+b

This membrane protein-related article is a stub. You can help Wikipedia by expanding it.v · Categories: Protein domains Protein families Transmembrane proteins Membrane protein stubs Wikimedia Foundation. 2010. Игры ⚽ Нужно сделать НИР? Kent Shocknek March 9, 1991 protest Look at other dictionaries: Cytochrome c — Cytochrome c, somatic Three dimensional structure of cytochrome c (green) with a heme molecule coordinating a central Iron atom (orange) …   Wikipedia Cytochrome — c with heme c. Cytochromes are, in general, membrane bound hemoproteins that contain heme groups and carry out electron transport. They are found either as monomeric proteins (e.g., cytochrome c) or as subunits of bigger enzymatic complexes that… …   Wikipedia Cytochrome b5 — Rat cytochrome b5 bound to heme Identifiers Symbol CYB5A Alt. symbols CYB5 …   Wikipedia Cytochrome b5 — Cytochrome Figure 1 : Un exemple de cytochrome : le cytochrome C. Les cytochromes sont des coenzymes intermédiaires de la chaîne respiratoire. Ils ont comme caractéristique commune d être constitués d une porphyrine complexée avec un… …   Wikipédia en Français Cytochrome c — Le cytochrome C Cytochrome C (cœur de cheval : BDP 1HRC) est une petite hémoprotéine (ou protéine à hème) associée avec la membrane interne de la mitochondrie …   Wikipédia en Français Cytochrome — Cytochrome,   Singular Cytochrom das, s, Zytochrome, zu den Hämoproteinen zählende Enzyme, die bei der Zellatmung, bei der Photosynthese und bei anderen biochemischen Vorgängen als Redoxkatalysatoren (Oxidoreduktasen) wirken. Cytochrome kommen in …   Universal-Lexikon cytochrome — ● cytochrome nom masculin Substance protéique pigmentée des cellules vivantes, localisée dans les mitochondries et indispensable à la respiration cellulaire. cytochrome n. m. BIOCHIM Pigment cellulaire contenant du fer et jouant un rôle essentiel …   Encyclopédie Universelle cytochrome c — cytochrome c. См. цитохром с. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь. Cytochrome — Cytochrome, in allen lebenden Zellen vorkommende, als Redoxsysteme an der Atmungskette und der Photosynthese beteiligte Chromoproteine; als Elektronenüberträger fungierende Oxidoreduktasen, die als prosthetische Gruppe den Porphyrinring Häm… …   Deutsch wörterbuch der biologie cytochrome — [sīt′ə krōm΄] n. [ CYTO + CHROME] any of several iron containing enzymes found in almost all animal and plant cells, very important in cell respiration …   English World dictionary 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”