Globular proteins motors

Even though dynein, kinesin, and myosin serve similar ATPase-dependent chemomechanical functions and have structural similarities, they do not appear to be related to each other in molecular terms. Their similarity lies in the overall shape of the molecule, which is composed of a pair of globular heads that bind microtubules and a fan-shaped tail piece (not present in myosin) that is suspected to carry the attachment site for membranous vesicles and other cytoplasmic components transported by MT. The cytoplasmic and axonemal dyneins are similar in structure (Hirokawa et al., 1989 Holzbaur and Vallee, 1994). Current studies on mutant phenotypes are likely to lead to a better understanding of the cellular roles of molecular motor proteins and their mechanisms of action (Endow and Titus, 1992). 

The consilient mechanism depicted in the elementary structures of Figure 8.2 are relevant to protein function arising out of association of globular components of molecular machines. The principles arise in almost textbook fashion in the function of the myosin II motor where the key charged species are ATP, ADP, and P, but in an important way also include the charged side chains (see section 8.5.3). 

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