Association of creatine kinase with rat heart mitochondria: high and low affinity binding sites and the involvement of phospholipids.

Cleavage of mitochondrial phosphatidylethanolamine (PE), phosphatidylcholine (PC) and cardiolipin (CL) by phospholipase A2 but not selective degradation of PE and PC by phospholipase C dissociates creatine kinase from rat heart mitochondria. Creatine kinase exhibits a high resistance against Triton X-100 solubilization up to concentrations of 0.05-0.1%. Scatchard plot of rebinding experiments using mitoplasts revealed the presence of both low and high affinity binding sites; the latter may account for the originally bound creatine kinase activity. It is suggested that creatine kinase is specifically bound to a CL containing domain of the inner mitochondrial membrane.