Functions of microtubule-based motors.

Microtubule-dependent transport is necessary for the intracellular functions of mitosis and axonal transport. In addition, a variety of microtubule-based vesicle movements occur in all cells. Recent studies indicate that the depolymerization of microtubules results in significant inhibition of the recycling of the ER membrane from the ER-Golgi transition compartment and inhibition of the maturation of endosomes. Other membrane traffic events are inhibited by microtubule depolymerization, but in most cases alternate pathways can accomplish the function in question. With a more in-depth understanding of these alternate pathways and improved tools for inhibiting motor function without affecting cytoplasmic viscosity, we should be able to determine more precisely the roles of motor-dependent vesicle transport.