Ubiquinol Cytochrome C Reductase (UQCR)

Using a PCR probe generated from bovine heart muscle cDNA to screen a human fibroblast cDNA library and a bovine heart muscle cDNA library, Islam et al. (1997) cloned full-length cDNA sequences encoding the human and bovine ubiquinol-cytochrome c reductase (cytochrome bc1 complex) 6.4 kD subunits. Both the human and bovine cDNAs encode putative proteins of 56 amino acids that share 88% sequence homology. Kyte-Doolittle analysis suggested the presence of a hydrophobic helix in the middle of the protein that could serve as a transmembrane domain. Northern blot analysis of human tissues detected a UQCR transcript of less than 1 kb at high levels in energy-requiring tissues such as heart and skeletal muscle. Southern blot analysis indicated that the protein is encoded by a single gene.