Part 2 with Ron Vale (UCSF, HHMI) discusses recent work from the Vale laboratory and other groups, on the mechanism of movement by dynein, a microtubule motor that is less well understood than kinesin and myosin. The lecture discusses the unusual properties of dynein stepping along microtubules, which have been uncovered using single molecule techniques. The nucleotide-driven structural changes in the dynein motor domain (elucidated by X-ray crystallography and electron microscopy) are also described. A model for dynein movement in the form of an animation is presented. However, much remains to be done in order to understand how this motor works and to test which elements of this model are correct.