Dynein structure and function.

The structure of dynein isolated from several sources follows the pattern first observed with Tetrahymena 22S dynein, which has three globular heads attached by three flexible strands to a root-like base. Recent biochemical data indicate that there is one ATPase site on each dynein head and that all three heads interact with microtubules in an ATP-sensitive manner. Accordingly, images of dynein in situ can be interpreted in terms of a model for crossbridge action where the roots of the bouquet anchor the dynein to the A-tubule and all three heads reach out to interact with the B-tubule in an ATP-dependent reaction to produce a force for sliding.