<p>The ubiquinol-cytochrome C reductase complex (cytochrome bc1 complex) is a respiratory multienzyme complex [<cite idref="PUB00006415"/>]. The bc1 complex contains 11 subunits; 3 respiratory subunits (cytochrome B, cytochrome C1, Rieske protein), 2 core proteins and 6 low molecular weight proteins. This family represents the 'hinge' protein of the complex which is thought to mediate formation of the cytochrome c1 and cytochrome c complex. Proteins in this entry from an alpha-helical hairpin.</p>This entry represents the structural domain found in these proteins.