Supplementary Figure 2: 2D structural analysis of flexible dynein.

(a) Masking and assembly strategy used to generate detailed 2D averages of the entire dynein molecule. Reference-free 2D class averages of dynein are determined using traditional methods. An example of one of these averages is shown on the far left. Due to the flexibility of the link between the head and tail domains, the structural features of this region are blurred. Soft masks (dotted lines) are used to isolate each head and the tail region of the molecule, and the particles contributing to each class are subjected to 2D analysis (grey arrows on left), revealing finer structural features of the tail and head domains. Next, the mask is removed from the aligned particles and new unmasked class averages are generated, allowing visualization of surrounding structural features. The kinked region of the HC, which is seen in the unmasked class averages of both the head and tail domains, is then correlated to align the components to generate a complete dynein molecule (right image). (b) A montage of masked class averages for the tail and head regions (upper and lower rows, respectively).