Fig. 2. Sub-tomogram averaged reconstructions.

a–c Overviews of sub-tomogram averaging of stars, empty- and full virion-like particles respectively using IMOD/PEET³². Scale bar length 500 Å. d Cross-section through the fivefold of map (b). Circled in red is density attributed to the polymerase. The σ1 spike protrudes from the surface (a σ1 trimer is fitted). e Surface rendering of the emClarity map for the empty virion-like particle coloured by radius (scale bar as for panel h), a σ3/μ1 heterohexamer is circled in red. f, g Fits of the models (see “Methods”) into the empty virion-like particle pseudo sixfold emClarity map, σ3 in purple, μ1 in cyan. h, i emClarity SLP map. h Coloured by radius. i Fit of λ1 subunits into the density, molecules A and B coloured green and red respectively. j Slice through the superposed sub-tomogram averaged emClarity maps; empty virion-like particle in blue and SLP in orange. The data were taken from five tomographic series (selected from 8 in total). Information on the number of particles used is given in Supplementary Table 1.