Isolated eWT AMII forms a heterogeneous mixture of minifilaments. Purified eWT monomers assembled in 10 mM imidazole (pH 7.0), 2.5 mM KCl, 1 mM ATP, and 1 mM MgCl2 form a mixture of clumped and staggered tetramers, hexamers, and octamers. Two images are shown for each structure; structures are identified in the left panels. (Scale bar, 100 nm.)