The UQCR11 gene, located on the p arm of chromosome 19 in position 13.3, is made up of 3 exons and is 8,329 base pairs in length.[6] The UQCR11 protein weighs 6.6 kDa and is composed of 56 amino acids.[7][8] This gene encodes the smallest known component of the ubiquinol-cytochrome c reductase complex, which is also known as Complex III and is part of the mitochondrial respiratory chain.[6] In vertebrates, Complex III contains 11 sub-units: 3 respiratory sub-units, 2 core proteins and 6 low-molecular weight proteins.[9][10] Proteobacterial complexes may contain as few as three sub-units.[11]
The UQCR11 protein may function as a binding factor for the iron-sulfur protein in Complex III, which is ubiquitous in human cells.[6] Complex III catalyzes the chemical reaction
QH2 + 2 ferricytochrome c Q + 2 ferrocytochrome c + 2 H+