Figure 3.

Speculative models for conformational changes of AAA proteins. (A) Target binding domains undergo a concerted, twisting conformational change. If a protein or protein complex is bound at two or more sites, it will be subject to mechanical stain by the conformational change. (B) A model for dynein-based motility based upon a conformational change in the ring. In this case, the shift in the AAA ring alters the angle of an embedded microtubule binding domain, which in turn produces a force that moves a microtubule. The dark gray spheres are the AAA domains and the smaller yellow sphere represent elements outside of the AAA domains (relative sizes are not necessarily accurate). Although not shown here, a conformational change may also have a vectoral component directed towards the center of the ring, as discussed in the text.