Stepping pattern of myoVa in the presence or absence of Mlph. Representative displacement versus time traces and histograms of step sizes fit with Gaussian distributions are shown. A, myoVa-HMM has a mean step size of 71.9 ± 19.4 nm (n = 161) and shows occasional back steps (arrow). B, myoVa shows two step populations with average sizes of 27.8 ± 6.5 nm and 64.0 ± 20.5 nm (n = 245). Dashed line shows the individual Gaussian fits to the slower shoulder and main peak. Arrow in the left panel points to a back step. C, in the presence of Mlph the distribution becomes uniform with an average step size of 63.0 ± 24.0 nm (n = 246). D, in the presence of Mlph-KA step sizes are uniform and show the same size as myoVa-HMM (71.7 ± 22.4 nm, n = 137). Conditions: 150 mm KCl, pH 7.4, 2–4 μm MgATP.