Figure 4.

(A) Actin-dependent MgATPase activity of the wild-type in the presence of various concentrations of actin. The activity was measured at 30°C. •, phosphorylated form at concentration of 120 μg/ml in the reaction mixture; ○, unphosphorylated form at a concentration of 120 μg/ml in the reaction mixture; ■, phosphorylated form at a concentration of 4.8 μg/ml in the reaction mixture; □, unphosphorylated form at a concentration of 4.8 μg/ml in the reaction mixture. (B) Fold of activation by RLC phosphorylation at various actin concentrations. ○, myosin at a concentration of 120 μg/ml in the reaction mixture; □, myosin at a concentration of 4.8 μg/ml in the reaction mixture.