ABSTRACT
This chapter discusses the mechanochemical cycle of a dynein monomer and the mechanism by which dynein dimers move processively and generate forces on microtubule filaments. The major barriers to study the mechanism of dynein motility were the lack of a recombinant expression system and a paucity of tools for observing the movement and conformational states of single motors. In vitro single molecule studies on dynein from yeast, Dictyostelium and vertebrates have significantly advanced our understanding of the mechanism and regulation of dynein motility. Processive movement of single dynein dimers is also observed for porcine brain dynein and mouse dynein/dynactin. Several dynein-associated enzymes have been shown to affect dynein motility directly. Optical trapping and fluorescence particle tracking studies have revealed that dynein stepping is fundamentally distinct from other motors. The size and direction of a dynein step is independent of the ATP concentration, but can be manipulated by external force.
