ABSTRACT
This chapter examines the measurement of the motile properties of single dynein molecules, in particular focusing on the studies on axonemal dynein using sea urchin sperm flagella and cytoplasmic dynein. It explains how mechanical force of bending is related to the regulation of dynein activity. Dynein that was first found in flagella and cilia is called the axonemal dynein, which has basically similar structures and functions to those of cytoplasmic dynein. By ATP hydrolysis, dynein converts the chemical energy into the mechanical work of microtubule sliding. Various signals including the central pair-related phosphorylation and the mechanical force are likely to release the ATP-inhibition and activate the dynein probably by simply controlling the stable ADP binding to regulatory nucleotide binding sites. Use of optical trap nanometry enabled to measure the force generated by dynein at a single molecular level in late 1990s. Purified dynein molecules isolated from doublet microtubule of sperm flagella retain an ability to move microtubules.
