A complete cDNA sequence for core I protein subunit of human ubiquinol-cytochrome c reductase

Core I protein is the largest subunit of ubiquinol-cytochrome c reductase. We have isolated a complete cDNA clone of 1575 bp encoding the precursor to this protein by screening a human fibroblast cDNA library. Nucleotide sequence comparison showed that the human core I protein cDNA is about 85% homologous with the reported bovine counter part but with a large difference in the length of coding region which consists of 480 amino acids in human and 362 amino acids in bovine. Human core I protein is presumed to contain a presequence of 34 amino acids. Amino acid sequence alignment study showed that the predicted human core I protein has a significant homology with other members of matrix processing peptidase (MPP) and processing enhancing protein (PEP) family.