What are the functions of Myosin?

myosin and actin work together to move your muscles

Myosin has a few different subtypes and a few different uses.  The most obvious one is in muscles, called Myosin II.  Myosin molecules are joined at the tails, facing in opposite directions.  When the signal is given, they pull on parallel actin filaments.  Since they myosin molecules face in opposite directions, they pull the actin filaments towards each other, shortening the muscle fiber and causing contraction.

Other types of myosin are used in transporting vesicles along the cytoskeleton within cells.  Actin is one of the major components of the cytoskeleton, so it serves as a pretty good "railroad."  Vesicles or proteins are attached to the tail end of myosin, which then "walks" down the actin filament in a specific direction.  This form of myosin is composed of two molecules joined at the tail - under extremely high resolution microscopy, it actually looks like the myosin is walking along on two legs.