[Physiological role of the creatine kinase system and the problem of regulating the activity of mitochondrial creatine kinase].

The review contains the analysis of present-day concepts on the physiological role of the creatine kinase system. A hypothesis on the buffering functions of the creatine kinase system which ensures a constant ATP level in cells and a hypothesis according to which phosphocreatine is a macroergic phosphate carrier from mitochondria to the sites of their utilization are considered. In connection with the creatine phosphate carrier hypothesis according to which the transport function of the creatine kinase system is provided for by an effective function of mitochondrial creatine kinase, feasible mechanisms of mitochondrial creatine kinase activity regulation are considered: as a result of creation of local concentration of nucleotide substrates as well as changes in the properties of creatine kinase itself which may result from the enzyme conversion from the membrane-bound to the free form or from the interconversion of oligomeric forms of the enzyme.