[Cytochrome c-induced acceleration of the reaction of muscle actin polymerization]

The reaction of rabbit skeletal muscle actin polymerization initiated by the addition of neutral salts is accelerated in the presence of mitochondrial cytochrome c. The observed effect is specific, since the addition of serum albumin does not change the initial velocity of this process. The dependence of the rate of actin polymerization and exogenous cytochrome c concentration correlates within the molar protein ratios from 43:1 to 9:1, respectively. The increase in the polymerization rate occurs immediately after addition of cytochrome c to the reaction mixture; however, the maximal effect is observed only after 5 min coincubation of the proteins. The ability of cytochrome c to stimulate this process is abolished at alkaline values of pH (8.5), which points to the significant role of the molecule positive charge which, in all probability, serves as a primer of the muscle actin polymerization reaction.