Structural Study of Heterogeneous Biological Samples by Cryoelectron Microscopy and Image Processing

Figure 7

ML procedure in the analysis of conformational changes of biocomplexes. Raw images are firstly assigned initial orientation angles using the initial model. That is typically done by projection matching. Then the ML approach is used to obtain 6 to 8 reconstructions. Each 3D model is visually examined in the area of interest; for a ligand presence, in this case the bound tRNA is highlighted in red. Images which were used to obtain the models with tRNA are extracted and subjected to the next round of classification. The following step involves extracting images corresponding to one or another conformation and then followed by refinement. The percentages below the structures in the top row indicate fractions of images from the entire dataset used to calculate these models, while in the second row the percentages are taken from the number of images supposedly containing the bound tRNA.