Regulation and recycling of myosin V.

Recently there has been considerable progress in our understanding of regulation for unconventional myosin-V through elucidation of the structure of its inactive conformation and the factors that affect stability of this conformation. The inactive conformation is a folded compact structure characterized by interactions between the myosin head and the C-terminal cargo binding domain. Concentrations of Ca2+ greater than 10 microM disrupt folding. The 3-D structure determined by cryoelectron tomography of 2-D arrays in one study and electron micrographs of isolated molecules reported in another reveal similar features, but suggest different F-actin affinities for the inactive conformation. This has raised the question of how inactive myosin-V is recycled to other sites for additional rounds of cargo transport.