Figure 1. EM analysis of glucagon receptor–mAb23 complex.
(a) Exemplary two-dimensional (2D) class average (sum of 343 individual particles) of negatively stained GCGR–mAb23 complex (left) and corresponding 3D surface representation of 3D map (∼30 Å resolution) determined using EM random conical tilt methods. 3D map is shown (right) in similar orientation to the 2D average (centre) and also rotated into an orientation convenient for comparison with the X-ray map. White scale bar, 50 nm. (b) Schematic interpretation of the domains in the EM map, rotated into an orientation convenient for comparison. (c) 3D envelope of the EM map (left), molecular model of the mAb23-bound full-length glucagon receptor structure based on mAb1-bound ECD (PDB code: 4ERS)30 and 7TM (PDB code: 4L6R)4 crystal structures (middle) and the molecular model fitted into the EM map (right). (d) View of panel c rotated 90° clockwise. Additional information on the EM maps is provided in Supplementary Fig. 1.