Ionic strength dependence of run lengths and termination rates at 1 mM ATP. Characteristic run length constants of FL- and HMM-myoV as a function of ionic strength. FLB-myoV (up triangles, dotted line), FLM-myoV (squares, dashed line), and YFP-FL-myoV (down triangles at 25 and 100 mM KCl only) have significantly shorter characteristic run lengths than the HMM-myoV (filled circles, solid line) at all KCl concentrations tested (T test; p ≤ 0.002).