Key parameters of diffusion of myosin V (Wildtype) and two myosin V loop 2 mutants.

Diffusion coefficients (D) were measured from the variance of the Gaussian fit function of the displacement histogram (Figure 3B). Values for maximum speed (Vmax) reflect the average maximum displacement along a microtubule during one frame interval (i.e., 5 frames per s) and were calculated from the respective number of analyzed diffusion events. Scan distances (xscan) were calculated as the distance between the two extreme positions the motor has scanned on the microtubule during one diffusion event. Association times (tA) represent the total time a myo V molecule spent on the microtubule during one diffusion event. Mean values for tA were measured from the exponential fit of the plotted histogram of single tA-values (Figure S3). Diffusion events are defined as events during which the myo V molecule has bound to the filament and subsequently started diffusing. Diffusion was quantified by single displacement measurements. Parameters of myo V diffusion on subtilisin-treated microtubules (S-microtubules) for Wildtype are shown in the bottom part. All parameters were obtained from experiments in 25 mM KCl. n represents the total number of analyzed diffusion and displacement events. Values represent mean ± S.E.M. Statistical significance at *P>0.05, **PPWildtype was determined using Student's t-Test.