Table 2.

Sliding velocity of actin filament on the myosin fragments

Myosin fragment	Sliding velocity,* μm/s
	Phosphorylated	Dephosphorylated
Skeletal HMM	4.78  ± 0.78	4.67  ± 0.58
Smooth HMM	0.58  ± 0.06	0
Expressed smooth 128-kDa fragment†	0.59  ± 0.11	0
Chimeric myosin	0.12  ± 0.03	0

^*Actin movement was observed in 30 mM KCl, 5 mM MgCl₂, 25 mM imidazole, 1 mM EGTA, 1% 2-mercaptoethanol, 0.5% metylcellulose, 4.5 mg/ml glucose, 216 μg/ml glucose oxidase, 36 μg/ml catalase, 2 mM ATP, pH 7.5 at 25°C. All values are mean velocities ± SD for three independent preparations. For each preparation, 30–40 actin filaments were measured to obtain an average velocity for each condition. 

^†Smooth MHC (Met¹–Ser¹¹¹⁰) was also coexpressed with smooth light chains in Sf9 cells and purified in the same way for the chimeric myosin (23, 24).