The primary structure of the precursor to core protein II, a putative member of mitochondrial processing protease family, of rat mitochondrial cytochrome bc1 complex deduced from cDNA sequence analysis.

Core protein II of mitochondrial cytochrome bc1 complex is the second largest nuclear-encoded subunit. We have isolated two overlapping cDNA clones encoding the precursor to this protein by screening a rat liver cDNA library, and determined the nucleotide sequence of the cDNAs. Based on the deduced amino acid sequence of the corresponding human precursor, the mature polypeptide of rat core protein II appears to consist of 438 amino acid residues with a molecular weight of 46,751, and to be formed as a precursor with an amino-terminal presequence. The mature form of the rat protein shows 83% and at most 24% homology with its human and yeast counterparts, respectively. Northern blot analysis showed that rat liver poly(A)+ RNA contains a single mRNA of approximately 2000 nucleotides for the core protein II.