UQCR11

UQCR11 (ubiquinol-cytochrome c reductase, complex III subunit XI) is a is_associated_with::protein that in humans is encoded by the UQCR11 is_associated_with::gene. UQCR11 is the smallest known component of is_associated_with::Complex III in the mitochondrial respiratory chain.

Structure
The UQCR11 gene, located on the p arm of is_associated_with::chromosome 19 in position 13.3, is made up of 3 exons and is 8,329 base pairs in length. The UQCR11 protein weighs 6.6 kDa and is composed of 56 amino acids. This gene encodes the smallest known component of the ubiquinol-cytochrome c reductase complex, which is also known as is_associated_with::Complex III and is part of the mitochondrial respiratory chain. In vertebrates, Complex III contains 11 subunits: 3 respiratory subunits, 2 core proteins and 6 low-molecular weight proteins. Proteobacterial complexes may contain as few as three subunits.

Function
The UQCR11 protein may function as a binding factor for the is_associated_with::iron-sulfur protein in is_associated_with::Complex III, which is ubiquitous in human cells. Complex III catalyzes the chemical reaction


 * QH2 + 2 ferricytochrome c $$\rightleftharpoons$$ Q + 2 ferrocytochrome c + 2 H+

Thus, the two substrates of Complex III are dihydroquinone (QH2) and ferri- (Fe3+) is_associated_with::cytochrome c, whereas its 3 products are is_associated_with::quinone (Q), ferro- (Fe2+) cytochrome c, and H+. This complex belongs to the family of is_associated_with::oxidoreductases, specifically those acting on diphenols and related substances as donor with a cytochrome as acceptor. This enzyme participates in is_associated_with::oxidative phosphorylation. It has four cofactors: cytochrome c1, cytochrome b-562, cytochrome b-566 and a 2-Iron is_associated_with::ferredoxin of the Rieske type.