Figure 5.

Actin-activated ATPase activity of S1 with increasing concentrations of the activator NEM-S1 in the absence of Ca²⁺. WT rates (circles) are the same in all panels, with the regression shown as a solid line for the WT and a dashed line for the mutants (squares). The Michaelis-Menten equation was fit to the data using a maximal rate of 6 s⁻¹ with varying K_M values (WT = 9.8 μM, D191H = 9.6 μM, R193H = 9.3 μM, R146G = 7.1 μM, and R146W = 6.7 μM). All conditions and corrections are similar to Fig. 4 with the exception that CaCl₂ was replaced with 1 mM EGTA.