UQCRH belongs to the UQCRH/QCR6 family. This is a component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex), which is part of the mitochondrial respiratory chain. This protein may mediate formation of the complex between cytochromes c and c1. Recombinant human UQCRH protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.