Extended Data Fig. 4: Characterization of the CD4–gp120–CCR5 complex by electron microscopy.

a, Representative image of the CD4–gp120–CCR5 complex in negative stain. The experiment was repeated independently at least 4 times with similar results. b, 2D averages of the negatively stained CD4–gp120–CCR5 complex. The box size of 2D averages is ~330 Å. c, 3D reconstruction of the negatively stained CD4–gp120–CCR5 complex, fitted with a gp120 structure containing an extended V3 loop (PDB ID: 2QAD²⁰), four-domain CD4 (PDB ID: 1WIO) and CCR5 (PDB ID: 4MBS). d, A representative cryo-EM image of the four-domain-CD4–gp120–CCR5 complex. Scale bar, 25 nm. Five independent large datasets were collected with similar results. e, 2D averages of the cryo-EM particle images show secondary structural features for both gp120 and CCR5.