Figure 6.

A flowchart for symmetry-free reconstruction using the dynamic masking technique. Starting with a collection of single particle images (whose icosahedral orientations are known) and the icosahedrally reconstructed map, a 3-D initial model and mask of the interested asymmetric features can be extracted and generated (red cylindrical area). The 3-D mask is used to generate a series of 2-D masks for the raw particle data. After these 2-D masks are dynamically applied to a particle image to extract the interested asymmetric features, the resulting masked images are aligned to reference projections of the 3-D model. This process is iterated, each time generating a new 3-D mask and model from the intermediate 3-D symmetry free reconstruction, until the asymmetric map converges.