Extended Data Fig. 6. HIV-1 Env trimers bound to one and two CD4 molecules are asymmetric with protomers adopting distinct conformational states.

a–h Rigid fitting of model of Env in a closed conformation (PDB:4ZMJ⁵⁹) (a–d) and an open conformation (PDB:5VN3) (e–h) into the density maps of Env bound to one CD4 molecule (a, e), two CD4 molecules (b, f), three CD4 molecules (c, g) and unliganded Env (d, h). Missing densities at the apex region of non-CD4 bound protomers are indicated by red arrowheads (a, b). Weak densities of the V1V2 loops on the non-CD4 bound protomers in the Env trimer bound to one CD4 molecule are indicated by purple arrows (e). Lack of density for the outward projecting V1V2 loops on the non-CD4 bound protomer in the Env trimer bound to two CD4 molecules is indicated by a red arrow (f).