Fig. 2.

Comparison of three spike conformations in context of trimer. (a) Two orthogonal views of the closed conformation (6vxx). (b) Two orthogonal views of the open-1 conformation (modeled after 6vyb). (c) Two orthogonal views of the open-2 conformation (modeled after PDB ID 6crz). (c,d) Two orthogonal views of the closed-to-open-1 movies with starting model in green and ending model in red, and intermediates in partial transparency. (e) Two orthogonal views of the open-1-to-open-2 movies. (f) Surface model for end-on view of model of the closed-to-open-1 movies. (g) Surface model for end-on view of model of the open-1-to-open-2 movies. See Video 1C for motions of symmetrized opening and closing of the central pore of the spike trimer associated with motions of the RBDs. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)