In vitro actin motility velocity varies linearly with the number of myosin impellers

Myosin power-shifting refers to the motors ability to change step-size during contraction on the fly without lowing actin filament sliding velocity. In the low step-size range single myosin translates actin with  = 6 nm while in the high range  = 8.1 nm. This corresponds approximately to the intermediate and long step-sizes from single myosins measured with the Qdot assay.120