Fig. 4.

The CD22 ectodomain adopts a tilted rod-like structure with low flexibility. a The eight primary 2D class average images of CD22 ECD obtained by negative-stain EM (top). The number of particle images in each class is indicated. 2D projections of the ab initio EM reconstruction (middle) and the SAXS 3D volume (bottom) account for nearly all particles classified in 2D classes. Scale bar represents 10 nm. b Views of the ab initio EM reconstruction (blue) and SAXS volume (yellow). The crystal structure of CD22_20–330,5A is shown as a surface fitted into the EM map and SAXS volume rendered with UCSF Chimera⁶³