Fig. 2.

She1 reduces stepping frequency of dynein, and increases fraction of backward and large steps. a Schematic of experimental setup. b Representative traces of GST–dynein₃₃₁ movement tracked with high precision in the presence of 1 mM ATP (green), 1 µM ATP (blue), or 1 mM ATP and either 10 nM She1 (red) or 25 nM She1 (brown), as indicated. Steps were detected using custom-written code (see Methods). c–e Histograms of step size distributions for GST–dynein₃₃₁ in the absence or presence of She1, and with either 1 µM or 1 mM ATP, as indicated (yellow boxes delineate steps >30 nm in either direction; see h). f Histograms of dwell times between steps (Supplementary Fig. 1c) were fit to a convolution of two exponential functions with equal decay constants, which are plotted here as stepping rate (error bars, standard error of the fit). g, h The fraction of forward (i.e., minus end-directed) and backward (i.e., plus end-directed) steps (g), or large steps (h; in either the plus, or minus end direction; see yellow boxes in c–e) of GST–dynein₃₃₁ in the absence or presence of the indicated concentrations of She1 and ATP (n = 320 steps from 4 motors for no She1; 419 steps from 10 motors for 10 nM She1; 571 steps from 8 motors for 25 nM She1; Supplementary Fig. 1)