Figure 1. Cryo electron microscopy of F-actin (undecorated actin) and the complex of F-actin, myosin-IE motor domain and tropomyosin (decorated actin).

(A) Subarea of an unprocessed image of the vitrified sample recorded at a defocus of 1 μm. The presence of a mixture of filament types is evident (decorated filaments marked by white arrows, undecorated filaments marked by black arrows). Filaments appear to be either decorated or undecorated over their complete length. Scale bar, 50 nm. (B) Representative class sums of the decorated filaments (35,374 segments). No classes with partial decoration were identified. Scale bar, 20 nm. (C) Representative class sums of the undecorated filaments (4,629 segments). No classes with partial decoration were identified. Scale bar, 20 nm.