ABSTRACT
All linear motors move or generate force by interacting with a cytoskeletal track (actin in the case of myosin and microtubules for kinesin and dynein), where they advance one step at a time in a unidirectional fashion not unlike walking using their heads as feet. The “inchworm” mechanism, where one head always remains bound to the substrate, has been proposed as a model for the movement of kinesin. Conformational changes in the nucleotide binding region are a critical contributor to movement and force generation in all linear motors, which in myosins consists of the light chain binding region and the stalk or coiled-coil region in kinesin and dynein. Like most biomotors, linear motors rely on ATP for force generation. The multistep process known as the “power stroke,” associated with the binding and hydrolysis of ATP and subsequent release of ADP, is believed to drive the forward movement of myosins in an exchange of weak and low binding states that causes the myosin to remain bound to and release from the actin substrate and results in forward movement. In this chapter, we primarily focus on myosin, which comprises over 2000 motors and 35 classes.
