Figure 1.

Fraction of beads binding (□) and moving (●) in the absence and the presence of 3 μM ATP, respectively, at various molar ratios of 22S dynein molecules to beads at the mixing. The plots are fitted to 1 − exp(−x/27.9) (broken line) and 1 − exp(−x/39.2) (solid line), where x is the molar ratio of 22S dynein to beads at the mixing. The dotted line indicates the probability, including geometric considerations, of a bead adsorbing two or more 22S dynein molecules that can simultaneously interact with a microtubule.