In vitro translation of canine mitochondrial creatine kinase messenger RNA.

The cell-free translation products of mRNA from canine myocardium were immunoprecipitated using antiserum specific for either the MM or mitochondrial creatine kinase subunit. The two subunits were shown to be encoded by the nuclear genome and translated from separate mRNAs. The mitochondrial subunit was translated as a polypeptide with a molecular weight approximately 6,000 greater than the mature form of the enzyme. In contrast, the M-subunit was translated as a polypeptide having a molecular weight identical to that of the mature cytosolic M-subunit. It is assumed that the mitochondrial subunit precursor must be proteolytically processed during translocation from the cytoplasm into mitochondria.