Tropomyosin: function follows structure.

Tropomyosin is known as the archetypal coiled coil, being the first to be sequenced and modeled. Studies of the structure and dynamics of tropomyosin, accompanied by biochemical and biophysical analyses of tropomyosin, mutants and model peptides, have revealed the complexity and subtleties required for tropomyosin function. Interruptions in the canonical coiled coil allow for bends and regions of local instability that are required for tropomyosin to bind to the helical actin filament. This chapter highlights insights gained from recent structural studies as they relate to variations in tropomyosin's coiled-coil structure that are essential for binding to actin and the relationship of periodic repeats to actin molecules in the filament.