Characterization of actin, actinin, and myosin isolated from Physarum

Abstract

Our work on actin and myosin from Physarum is briefly reviewed, and the physicochemical properties of these proteins are compared with those of the corresponding proteins obtained from rabbit striated muscle. In this article both similarities and differences between these preparations are emphasized in order to characterize the Physarum actomyosin system. Some properties of Physarum actinin, a regulatory protein of actin polymerization, are also reported. Finally, the assembly and disassembly of F-actin filaments in the reversible superprecipitation of Physarum actomyosin are demonstrated. The mechanism of generation of the motive force for protoplasmic streaming in plasmodium is discussed in the light of these findings.