FIGURE 5.
Actin-activated ATPase activities of Myo19-truncated constructs. ATPase activities of M19-1IQ (A), M19-2IQ (B), and M19-3IQ (C) were measured in a solution containing 50 mm NaCl, 20 mm MOPS (pH 7.0), 1 mm MgCl2, 1 mm EGTA, 0.25 mg/ml of BSA, 1 mm DTT, 0.5 mm ATP, 2.5 mm phosphoenol pyruvate, 20 units/ml of pyruvate kinase, 4 μm RLC9, 4 μm RLC12b, and 0–80 μm actin. ATPase activity of Myo5a-1IQ (D) was measured similarly except that RLCs was substituted with 12 μm CaM. Curves are the least squares fits of the data points based upon the equation, V = (Vmax × [actin]/Kactin + [actin]). Although multiple independent assays of at least 2 preparations have been performed, data from a single assay are presented. Vmax and Kactin from multiple assays are summarized in Table 1.