ABSTRACT
Dynein, kinesin, and myosin form the three families of molecular motors that are responsible for the motility of eukaryotic cells [1-3]. In recent years, numerous studies have been performed to characterize the structure, function, and mobility of these protein motors. In particular, the use of single molecule spectroscopic techniques have made possible the direct observation and quantitative measurement of the motions and mechanical responses of these motor proteins. The understanding of the chemomechanical coupling mechanism, through which chemical energy of adenosine triphosphate (ATP) hydrolysis is used to perform mechanical work, has been the focus of most research studies. Generally speaking, these protein motors all follow a similar strategy [4,5] in which the motor core binds and hydrolyzes ATP and coordinates the chemical energy release with the conformational changes that lead to physical motions, although much of the molecular mechanism is still not known. Chemical transitions including ATP binding and hydrolysis and/or adenosine diphosphate (ADP) and inorganic phosphate (Pi) release in the motor domain regulate the binding of a motor protein to its track, such as the microtubule for kinesin and dynein and the actin lament for myosin, and induce the directional or
oscillatory motions of the motor proteins along the tracks. The proper functions of these motor proteins are essential for the survival and reproduction of cells. Their malfunctions are known to be linked to a large number of diseases.
