When using these animations in any way, please acknowledge:
Matthew L. Walker, Stan A. Burgess, James R. Sellers, Fei Wang, John A. Hammer III, John Trinick & Peter J. Knight. Two-headed Binding of a Processive Myosin to F-actin. Nature, 405, 804-807 (2000).
The negatively stained images have a resolution of ~2 nm, but the detail in individual images is obscured by noise from the carbon substrate, the stain and random distortions of the molecules. By averaging many images the detail emerges. We have developed computing methods to produce averaged images of the leading and trailing heads of molecules attached by both heads. These are shown below in the right and left panels, respectively, and are taken from the paper referred to above. There is some blurring of the regulatory domains due to their variable positions, but it is clear that there is a major difference between the leading and trailing orientations. There is little difference in the motor domains and the actin subunits to which they are attached. This provides direct evidence that a change in angle between the motor and regulatory domains in attached heads is the basis of myosin movement. The shape change seen in the attached head is easier to see in myosin V because the regulatory domain is very long, but the underlying mechanism is probably common to all myosins. The scale bar is 20 nm.