Figure 3.2 Models of the motion of muscle myosin and conventional kinesin [8]. (A). Frame 1: Muscle myosin is a dimer oftwo identical motor heads, anchored to a thick filament (top). Frames 2-4 show docking of heads on actin filament (lower), which serves to move the actin. The motion is about 10 nm per ATP hydrolyzed. (B). The two heads of the kinesin dimer move along a tubulin filament as indicated in Frames 1-4. In these frames the coiled coil extends to the top and to the attached cargo. The step length is about 8 nm. The head motion is associated with hydrolysis of ATP to ADP. The scale bar in A is 6 nm; that in B is 4 nm. (Taken from [8])

The details of the muscle myosin movement have been recently confirmed [18,19]. It is now definitely known that the trailing muscle myosin head leaps ahead of the forward fixed head, in a motion similar to bipedal walking, or hand-over-hand rope climbing.

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