BCS1 ubiquinol-cytochrome c reductase complex chaperone
Last updated 1 Aug 2025
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The BCS1L gene provides instructions for making a protein that functions in cell structures called mitochondria, which convert the energy from food into a form that cells can use. The BCS1L protein is critical for the formation of a group of proteins known as complex III. Specifically, BCS1L adds a component called Rieske Fe/S protein to the complex. In mitochondria, complex III performs one step of the multistep process known as oxidative phosphorylation, in which oxygen and simple sugars are used to create adenosine triphosphate (ATP), the cell's main energy source.
Normal function
The BCS1L gene provides instructions for making a protein that functions in cell structures called mitochondria, which convert the energy from food into a form that cells can use. The BCS1L protein is critical for the formation of a group of proteins known as complex III. Specifically, BCS1L adds a component called Rieske Fe/S protein to the complex. In mitochondria, complex III performs one step of the multistep process known as oxidative phosphorylation, in which oxygen and simple sugars are used to create adenosine triphosphate (ATP), the cell's main energy source.
As a byproduct of its action in oxidative phosphorylation, complex III produces reactive oxygen species, which are harmful molecules that can damage DNA and tissues. The reactive oxygen species produced by complex III are thought to also play a role in normal cell signaling, particularly when levels of oxygen in the body are low (hypoxia).
Some researchers believe the BCS1L protein is involved in the breakdown (metabolism) of iron, although the mechanism is unknown.
Conditions referring to this gene or chromosome
Other names
BC1 (ubiquinol-cytochrome c reductase) synthesis-like
BCS1
BCS1-like protein
BCS1_HUMAN
h-BCS1
Hs.6719
mitochondrial chaperone BCS1
mitochondrial complex III assembly
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Further reading and references
- BCS1 ubiquinol-cytochrome c reductase complex chaperone; MedlinePlus, National Library of Medicine.
- Bleier L, Drose S. Superoxide generation by complex III: from mechanistic rationales to functional consequences. Biochim Biophys Acta. 2013 Nov-Dec;1827(11-12):1320-31. doi: 10.1016/j.bbabio.2012.12.002. Epub 2012 Dec 23.
- de Lonlay P, Valnot I, Barrientos A, Gorbatyuk M, Tzagoloff A, Taanman JW, Benayoun E, Chretien D, Kadhom N, Lombes A, de Baulny HO, Niaudet P, Munnich A, Rustin P, Rotig A. A mutant mitochondrial respiratory chain assembly protein causes complex III deficiency in patients with tubulopathy, encephalopathy and liver failure. Nat Genet. 2001 Sep;29(1):57-60. doi: 10.1038/ng706.
- Fernandez-Vizarra E, Bugiani M, Goffrini P, Carrara F, Farina L, Procopio E, Donati A, Uziel G, Ferrero I, Zeviani M. Impaired complex III assembly associated with BCS1L gene mutations in isolated mitochondrial encephalopathy. Hum Mol Genet. 2007 May 15;16(10):1241-52. doi: 10.1093/hmg/ddm072. Epub 2007 Apr 2.
- Gil-Borlado MC, Gonzalez-Hoyuela M, Blazquez A, Garcia-Silva MT, Gabaldon T, Manzanares J, Vara J, Martin MA, Seneca S, Arenas J, Ugalde C. Pathogenic mutations in the 5' untranslated region of BCS1L mRNA in mitochondrial complex III deficiency. Mitochondrion. 2009 Sep;9(5):299-305. doi: 10.1016/j.mito.2009.04.001. Epub 2009 Apr 21.
- Hinson JT, Fantin VR, Schonberger J, Breivik N, Siem G, McDonough B, Sharma P, Keogh I, Godinho R, Santos F, Esparza A, Nicolau Y, Selvaag E, Cohen BH, Hoppel CL, Tranebjaerg L, Eavey RD, Seidman JG, Seidman CE. Missense mutations in the BCS1L gene as a cause of the Bjornstad syndrome. N Engl J Med. 2007 Feb 22;356(8):809-19. doi: 10.1056/NEJMoa055262.
- Moran M, Marin-Buera L, Gil-Borlado MC, Rivera H, Blazquez A, Seneca S, Vazquez-Lopez M, Arenas J, Martin MA, Ugalde C. Cellular pathophysiological consequences of BCS1L mutations in mitochondrial complex III enzyme deficiency. Hum Mutat. 2010 Aug;31(8):930-41. doi: 10.1002/humu.21294.
- Visapaa I, Fellman V, Vesa J, Dasvarma A, Hutton JL, Kumar V, Payne GS, Makarow M, Van Coster R, Taylor RW, Turnbull DM, Suomalainen A, Peltonen L. GRACILE syndrome, a lethal metabolic disorder with iron overload, is caused by a point mutation in BCS1L. Am J Hum Genet. 2002 Oct;71(4):863-76. doi: 10.1086/342773. Epub 2002 Sep 5.
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