Fig. 4: The RBDs form a trimeric assembly at the apex of the full-length Env.

a Three SFV RBDD protomers were fitted in the 9 Å cryo-EM map (EMBD: 4013) obtained by cryo-EM 3D reconstruction of the full-length PFV Env expressed on viral vector particles13. The map is shown in light gray surface, and RBDs in cartoon mode, with each protomer colored differently (yellow, white, light blue). b The three RBDs, fitted as explained in panel a, are shown to illustrate that the α2 and η4 helices, which carry the HS-binding residues (K342, R343, R359, R369), and the N-linked glycosylations (N6, N7, N7’, N8, N9 and N11) point outward and are solvent accessible. The boxed region on the left panel is magnified and displayed on the right panel (only one protomer, colored in white, is represented for clarity purposes). c The views at the trimeric RBD arrangement from the top i.e. looking at the membrane (left) and bottom i.e. looking from the membrane (right) are shown. The RBDs form interprotomer contacts via the L1-L4 in the upper domain. The loops belonging to each protomer are designated as L, L’, and L”. Images were generated in Chimera29.