EXPERIMENTAL FIGURE 17-9 The two ends of a myosin-decorated actin filament grow at different rates. When short actin filaments are decorated with myosin S1 heads to reveal the orientation of the filaments and then used to nucleate actin polymerization, G-actin monomers are added much more efficiently to the (+) ends than to the (−) ends of the nucleating filaments.

[Courtesy Thomas Pollard.]