Cytochrome c is a well characterized, mobile electron transport protein that is essential to energy conversion in all aerobic organisms. Cytochrome b associates with cytochrome c subunit 1 and the Rieske protein to form complex III (also designated cytochrome bc1 complex), which is involved in cellular respiration. Ubiquinol cytochrome c reductase (UQCRFS1), also referred to as Rieske iron-sulfur protein, represents an important subunit of complex III of the mitochondrial respiratory chain that transfers electrons from ubiquinol to cytochrome c. The UQCRFS1 complex is made up of 3 respiratory subunits (cytochrome b, cytochrome c1, Rieske protein), 2 core proteins, and 6 low-molecular weight proteins. Ubiquinol cytochrome-c reductase complex core protein 2 (UQCRC2) represents one of the core proteins of UQCRFS1, and it is required for the assembly of the complex.