Table 5.

ATPase activity and velocity of WT and mutant Dictyostelium myosin II

	ATP ase activity* (Pi/head/s)	Velocity (μm/s)†
WT	1.4 ± 0.2	2.4 ± 0.2
S564K	2.4 ± 0.3	2.4 ± 0.2
R620A K622A	0.12 ± 0.01	0
S564K/R620A K622A	0.45 ± 0.06	3.1 ± 0.4‡

Actin-activated ATPase activity and velocity of wild type and mutant Dictyostelium myosins

*Values are averages ± SD of at least three measurements on two independent preparations. Each value was obtained by subtracted activities in the absence of actin from the measured values in the presence of 95 μM actin.

^†Values are averages ± SD of 20–30 actin filaments on two independent preparations.

^‡Velocity of S564K/R620A K622A myosin was done in the presence of 0.8% methylcellulose.