Actin purified from Dictyostelium amoebae shares identical molecular weight, specific activity for heavy meromyosin activation, and structural properties with muscle actin.
The study demonstrates that actin from Dictyostelium amoebae shares key biochemical and structural properties with muscle actin, including ATPase activation and paracrystal formation.
Abstract Actin, an apparently universal component of eukaryotic cells, has been purified from Dictyostelium amoebae to electrophoretic homogeneity. Purification was facilitated by newly discovered solubility properties of actomyosin in 30% sucrose. A quantitative assay for the Dictyostelium actin is described which is based on its ability to activate muscle heavy meromyosin ATPase activity. The specific activity of purified amoeba actin for activation of heavy meromyosin is nearly the same as that of purified muscle actin. The molecular weight of the Dictyostelium actin is identical with that of muscle actin, as judged by co-electrophoresis on sodium dodecyl sulfate acrylamide gels. The amoeba actin, like muscle actin, forms Mg2+-paracrystals with a helical repeat of about 360 A. Some of the Dictyostelium actin is associated with membrane in a MgATP-stable linkage. Myosin is found in membrane preparations in a MgATP-labile linkage, presumably due to association with the membranelinked actin.
Spudich et al. (Sun,) reported a other. Actin purification from Dictyostelium amoebae vs. Muscle actin was evaluated on Biochemical and structural properties of Dictyostelium actin. Actin purified from Dictyostelium amoebae shares identical molecular weight, specific activity for heavy meromyosin activation, and structural properties with muscle actin.