Unconventional myosins at the crossroad of signal transduction and cytoskeleton remodeling

The cytoplasm of eukaryotic cells is a complex milieu and unraveling how it s unique cytoarchitecture is achieved and maintained is a central theme in modern cell biology. The actin cytoskeleton is essential for the maintenanc e of cell shape and locomotion, and also provides tracks for active intrace llular transport. Myosins, the actin-dependent motor proteins form a superf amily of at least 15 structural classes and have been identified in a wide variety of organisms, making the presence of actin and myosins a hallmark f eature of eukaryotes. Direct connections of myosins to a variety of cellula r tasks are now emerging, such as in cytokinesis, phagocytosis, endocytosis , polarized secretion and exocytosis, axonal transport. Recent studies reve al that myosins also play an essential role in many aspects of signal trans duction and neurosensation.