Fig. 1.

Cofilin–actin interaction and structural changes. (A) A bare actin filament contains actin subunits (light blue rectangles) with longitudinal actin–actin bonds (small red squares). Numbering of actin subunits is similar to Huehn et al. (16). (B) An actin filament with a single cofilin molecule (green cylinder) contains only one actin subunit with altered conformation (orange rectangle). (C) Clustered binding of cofilin alters conformation of actin only at subunits that directly contact with cofilin. The arrows indicate fragile points where severing may occur.