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CYTB
Identifiers
Aliases	CYTB, MTCYB, MT-CYB, cytochrome b
External IDs	OMIM: 516020; MGI: 102501; HomoloGene: 5013; GeneCards: CYTB; OMA:CYTB - orthologs
Gene location (Human) Chr. Mitochondrial DNA (human) Band n/a Start 14,747 bp End 15,887 bp
Gene location (Mouse) Chr. Mitochondrial DNA (mouse) Band n/a Start 14,145 bp End 15,288 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in apex of heart gastric mucosa right lobe of thyroid gland left ventricle putamen caudate nucleus left uterine tube nucleus accumbens subcutaneous adipose tissue right adrenal cortex Top expressed in neural layer of retina Hypothalamus striatum of neuraxis adrenal gland dentate gyrus of hippocampal formation granule cell right kidney primary visual cortex superior frontal gyrus Cerebellum cerebellar cortex More reference expression data BioGPS n/a
Gene ontology Molecular function ubiquinol-cytochrome-c reductase activity protein-containing complex binding metal ion binding electron transfer activity oxidoreductase activity heme binding Cellular component mitochondrial respiratory chain complex III integral component of membrane respiratory chain complex III membrane mitochondrion mitochondrial inner membrane respirasome integral component of mitochondrial inner membrane protein-containing complex Biological process response to hypoxia response to glucagon response to cadmium ion response to organic cyclic compound response to nutrient response to copper ion response to hyperoxia hyperosmotic salinity response response to heat response to calcium ion animal organ regeneration response to organonitrogen compound response to hormone response to mercury ion response to ethanol response to toxic substance response to cobalamin proton transmembrane transport respiratory electron transport chain mitochondrial electron transport, ubiquinol to cytochrome c electron transport coupled proton transport Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 4519 17711 Ensembl ENSG00000198727 ENSMUSG00000064370 UniProt P00156 P00158 RefSeq (mRNA) n/a n/a RefSeq (protein) n/a NP_904340 Location (UCSC) Chr M: 0.01 – 0.02 Mb Chr M: 0.01 – 0.02 Mb PubMed search
Wikidata
View/Edit Human View/Edit Mouse

Cytochrome b is a protein that in humans is encoded by the MT-CYB gene. Its gene product is a subunit of the respiratory chain protein ubiquinol–cytochrome c reductase (UQCR, complex III or cytochrome bc₁ complex), which consists of the products of one mitochondrially encoded gene, MT-CYB (mitochondrial cytochrome b), and ten nuclear genes—UQCRC1, UQCRC2, CYC1, UQCRFS1 (Rieske protein), UQCRB, "11kDa protein", UQCRH (cyt c₁ Hinge protein), Rieske protein presequence, "cyt c₁ associated protein", and Rieske-associated protein.

Structure

The MT-CYB gene is located on the p arm of mitochondrial DNA in position 12 and spans 1,140 base pairs. The gene produces a 42.7 kDa protein named cytochrome b composed of 380 amino acids. Cytochrome b is an integral membrane protein with hydrophobic properties. The catalytic core of the enzyme is composed of eight transmembrane helices, the iron-sulfur protein, and cytochrome c1. Cytochrome b is a fundamental component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex) that is part of the mitochondrial respiratory chain. The b-c1 complex mediates electron transfer from ubiquinol to cytochrome c. The structure of the complex is a symmetric homodimer. It is composed of eleven structural subunits, including one mitochondrial genome encoded cytochrome b and ten other nucleus encoded subunits. These subunits include three respiratory subunits (MT-CYB, CYC1 and UQCRFS1), two core proteins (UQCRC1 and UQCRC2) and six low-molecular weight proteins (UQCRH/QCR6, UQCRB/QCR7, UQCRQ/QCR8, UQCR10/QCR9, UQCR11/QCR10 and a cleavage product of UQCRFS1). The total molecular mass of the complex is about 450 kDa.

Function

The mitochondrial cytochrome b is fundamental for the assembly and function of Complex III of the mitochondrial respiratory chain. Complex III is responsible for the catalysis of electron transfer from coenzyme Q to cytochrome c in the mitochondrial respiratory chain by translocating protons concomitantly across the inner membrane of the mitochondria. The transfer of electrons then contributes to the generation of a proton gradient across the mitochondrial membrane that is then used for ATP synthesis.

Clinical significance

Mutations in MT-CYB can result in mitochondrial deficiencies and associated disorders. It is majorly associated with a complex III deficiency, a deficiency in an enzyme complex which catalyzes electron transfer from coenzyme Q to cytochrome c in the mitochondrial respiratory chain. A complex III deficiency can result in a highly variable phenotype depending on which tissues are affected. Most frequent clinical manifestations include progressive exercise intolerance and cardiomyopathy. Occasional multisystem disorders accompanied by exercise intolerance may arise as well, in forms of deafness, mental retardation, retinitis pigmentosa, cataract, growth retardation, and epilepsy. Other phenotypes include mitochondrial encephalomyopathy, mitochondrial myopathy, Leber hereditary optic neuropathy, muscle weakness, myoglobinuria, blood acidosis, renal tubulopathy, and more. Complex III deficiency is known to be rare among mitochondrial diseases and may follow a maternal or mendelian mode of inheritance due to its duality of genetic origin.

References

1. ^ GRCh38: Ensembl release 89: ENSG00000198727 – Ensembl, May 2017
2. ^ GRCm38: Ensembl release 89: ENSMUSG00000064370 – Ensembl, May 2017
3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
5. ^ "Entrez Gene: CYTB cytochrome b".
6. Zong NC, Li H, Li H, Lam MP, Jimenez RC, Kim CS, Deng N, Kim AK, Choi JH, Zelaya I, Liem D, Meyer D, Odeberg J, Fang C, Lu HJ, Xu T, Weiss J, Duan H, Uhlen M, Yates JR, Apweiler R, Ge J, Hermjakob H, Ping P (Oct 2013). "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research. 113 (9): 1043–53. doi:10.1161/CIRCRESAHA.113.301151. PMC 4076475. PMID 23965338.
7. "cytochrome b". Cardiac Organellar Protein Atlas Knowledgebase (COPaKB).
8. ^ Fragaki K, Procaccio V, Bannwarth S, Serre V, O'Hearn S, Potluri P, Augé G, Casagrande F, Caruba C, Lambert JC, Paquis-Flucklinger V (September 2009). "A neonatal polyvisceral failure linked to a de novo homoplasmic mutation in the mitochondrially encoded cytochrome b gene". Mitochondrion. 9 (5): 346–52. doi:10.1016/j.mito.2009.06.002. PMID 19563916.
9. ^ "UniProtKB - P00156 (CYB_HUMAN)". The UniProt Consortium.
10. ^ Gil Borlado MC, Moreno Lastres D, Gonzalez Hoyuela M, Moran M, Blazquez A, Pello R, Marin Buera L, Gabaldon T, Garcia Peñas JJ, Martín MA, Arenas J, Ugalde C (September 2010). "Impact of the mitochondrial genetic background in complex III deficiency". PLOS ONE. 5 (9): e12801. Bibcode:2010PLoSO...512801G. CiteSeerX 10.1.1.350.7243. doi:10.1371/journal.pone.0012801. PMC 2941448. PMID 20862300.
11. Massie R, Wong LJ, Milone M (July 2010). "Exercise intolerance due to cytochrome b mutation". Muscle & Nerve. 42 (1): 136–40. doi:10.1002/mus.21649. PMID 20544923. S2CID 23759055.
12. Baum H, Rieske JS, Silman HI, Lipton SH (March 1967). "On the mechanism of electron transfer in complex iii of the electron transfer chain". Proceedings of the National Academy of Sciences of the United States of America. 57 (3): 798–805. Bibcode:1967PNAS...57..798B. doi:10.1073/pnas.57.3.798. PMC 335578. PMID 16591533.

Further reading

• Ingman M, Kaessmann H, Pääbo S, Gyllensten U (Dec 2000). "Mitochondrial genome variation and the origin of modern humans". Nature. 408 (6813): 708–13. Bibcode:2000Natur.408..708I. doi:10.1038/35047064. PMID 11130070. S2CID 52850476.
• Maca-Meyer N, González AM, Larruga JM, Flores C, Cabrera VM (2003). "Major genomic mitochondrial lineages delineate early human expansions". BMC Genetics. 2: 13. doi:10.1186/1471-2156-2-13. PMC 55343. PMID 11553319.
• Herrnstadt C, Elson JL, Fahy E, Preston G, Turnbull DM, Anderson C, Ghosh SS, Olefsky JM, Beal MF, Davis RE, Howell N (May 2002). "Reduced-median-network analysis of complete mitochondrial DNA coding-region sequences for the major African, Asian, and European haplogroups". American Journal of Human Genetics. 70 (5): 1152–71. doi:10.1086/339933. PMC 447592. PMID 11938495.
• Silva WA, Bonatto SL, Holanda AJ, Ribeiro-Dos-Santos AK, Paixão BM, Goldman GH, Abe-Sandes K, Rodriguez-Delfin L, Barbosa M, Paçó-Larson ML, Petzl-Erler ML, Valente V, Santos SE, Zago MA (Jul 2002). "Mitochondrial genome diversity of Native Americans supports a single early entry of founder populations into America". American Journal of Human Genetics. 71 (1): 187–92. doi:10.1086/341358. PMC 384978. PMID 12022039.
• Yamasoba T, Goto Yi, Oka Y, Nishino I, Tsukuda K, Nonaka I (Jun 2002). "Atypical muscle pathology and a survey of cis-mutations in deaf patients harboring a 1555 A-to-G point mutation in the mitochondrial ribosomal RNA gene". Neuromuscular Disorders. 12 (5): 506–12. doi:10.1016/S0960-8966(01)00329-7. PMID 12031626. S2CID 37695849.
• Mishmar D, Ruiz-Pesini E, Golik P, Macaulay V, Clark AG, Hosseini S, Brandon M, Easley K, Chen E, Brown MD, Sukernik RI, Olckers A, Wallace DC (Jan 2003). "Natural selection shaped regional mtDNA variation in humans". Proceedings of the National Academy of Sciences of the United States of America. 100 (1): 171–6. Bibcode:2003PNAS..100..171M. doi:10.1073/pnas.0136972100. PMC 140917. PMID 12509511.
• Mancuso M, Filosto M, Stevens JC, Patterson M, Shanske S, Krishna S, DiMauro S (May 2003). "Mitochondrial myopathy and complex III deficiency in a patient with a new stop-codon mutation (G339X) in the cytochrome b gene". Journal of the Neurological Sciences. 209 (1–2): 61–3. doi:10.1016/S0022-510X(02)00462-8. PMID 12686403. S2CID 31605529.
• Ingman M, Gyllensten U (Jul 2003). "Mitochondrial genome variation and evolutionary history of Australian and New Guinean aborigines". Genome Research. 13 (7): 1600–6. doi:10.1101/gr.686603. PMC 403733. PMID 12840039.
• Kong QP, Yao YG, Sun C, Bandelt HJ, Zhu CL, Zhang YP (Sep 2003). "Phylogeny of east Asian mitochondrial DNA lineages inferred from complete sequences". American Journal of Human Genetics. 73 (3): 671–6. doi:10.1086/377718. PMC 1180693. PMID 12870132.
• Kong QP, Yao YG, Liu M, Shen SP, Chen C, Zhu CL, Palanichamy MG, Zhang YP (Oct 2003). "Mitochondrial DNA sequence polymorphisms of five ethnic populations from northern China". Human Genetics. 113 (5): 391–405. doi:10.1007/s00439-003-1004-7. PMID 12938036. S2CID 6370358.
• Maca-Meyer N, González AM, Pestano J, Flores C, Larruga JM, Cabrera VM (Oct 2003). "Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography". BMC Genetics. 4: 15. doi:10.1186/1471-2156-4-15. PMC 270091. PMID 14563219.
• Haut S, de Villemeur TB, Brivet M, Guiochon-Mantel A, Boutron A, Rustin P, Legrand A, Slama A (Mar 2004). "The deleterious G15498A mutation in mitochondrial DNA-encoded cytochrome b may remain clinically silent in homoplasmic carriers". European Journal of Human Genetics. 12 (3): 220–4. doi:10.1038/sj.ejhg.5201132. PMID 14735157.
• Palanichamy MG, Sun C, Agrawal S, Bandelt HJ, Kong QP, Khan F, Wang CY, Chaudhuri TK, Palla V, Zhang YP (Dec 2004). "Phylogeny of mitochondrial DNA macrohaplogroup N in India, based on complete sequencing: implications for the peopling of South Asia". American Journal of Human Genetics. 75 (6): 966–78. doi:10.1086/425871. PMC 1182158. PMID 15467980.
• Starikovskaya EB, Sukernik RI, Derbeneva OA, Volodko NV, Ruiz-Pesini E, Torroni A, Brown MD, Lott MT, Hosseini SH, Huoponen K, Wallace DC (Jan 2005). "Mitochondrial DNA diversity in indigenous populations of the southern extent of Siberia, and the origins of Native American haplogroups". Annals of Human Genetics. 69 (Pt 1): 67–89. doi:10.1046/j.1529-8817.2003.00127.x. PMC 3905771. PMID 15638829.
• Rajkumar R, Banerjee J, Gunturi HB, Trivedi R, Kashyap VK (2006). "Phylogeny and antiquity of M macrohaplogroup inferred from complete mt DNA sequence of Indian specific lineages". BMC Evolutionary Biology. 5: 26. doi:10.1186/1471-2148-5-26. PMC 1079809. PMID 15804362.
• Thangaraj K, Chaubey G, Kivisild T, Reddy AG, Singh VK, Rasalkar AA, Singh L (May 2005). "Reconstructing the origin of Andaman Islanders". Science. 308 (5724): 996. doi:10.1126/science.1109987. PMID 15890876. S2CID 12011171.
• Blakely EL, Mitchell AL, Fisher N, Meunier B, Nijtmans LG, Schaefer AM, Jackson MJ, Turnbull DM, Taylor RW (Jul 2005). "A mitochondrial cytochrome b mutation causing severe respiratory chain enzyme deficiency in humans and yeast". The FEBS Journal. 272 (14): 3583–92. doi:10.1111/j.1742-4658.2005.04779.x. PMID 16008558.
• Kivisild T, Shen P, Wall DP, Do B, Sung R, Davis K, Passarino G, Underhill PA, Scharfe C, Torroni A, Scozzari R, Modiano D, Coppa A, de Knijff P, Feldman M, Cavalli-Sforza LL, Oefner PJ (Jan 2006). "The role of selection in the evolution of human mitochondrial genomes". Genetics. 172 (1): 373–87. doi:10.1534/genetics.105.043901. PMC 1456165. PMID 16172508.
• Behar DM, Metspalu E, Kivisild T, Achilli A, Hadid Y, Tzur S, Pereira L, Amorim A, Quintana-Murci L, Majamaa K, Herrnstadt C, Howell N, Balanovsky O, Kutuev I, Pshenichnov A, Gurwitz D, Bonne-Tamir B, Torroni A, Villems R, Skorecki K (Mar 2006). "The matrilineal ancestry of Ashkenazi Jewry: portrait of a recent founder event". American Journal of Human Genetics. 78 (3): 487–97. doi:10.1086/500307. PMC 1380291. PMID 16404693.
• van Holst Pellekaan SM, Ingman M, Roberts-Thomson J, Harding RM (Oct 2006). "Mitochondrial genomics identifies major haplogroups in Aboriginal Australians". American Journal of Physical Anthropology. 131 (2): 282–94. doi:10.1002/ajpa.20426. PMID 16596590.

• Human mitochondrial genes
• Mitochondrial proteins