FIG 8.

Comparison of U₁ and U₂ Env(−) structures. (A) Protomer 2 of the state-U₁ and state-U₂ models are superposed, showing that protomer 1 and protomer 3 are rotated 4.0° and 2.8°, respectively. (B) Three protomers of the state-U₁ model are superposed. (C) Three protomers of the state-U₂ model are superposed. (D) With protomer 2 of the state-U₁ and state-U₂ models superposed, the Cα distances between the same residues on the U₁ and U₂ structures are measured for four residues (from i to iv, T90, D230, S481, and N392). In the side views of Env(−) shown in panels B to D, gp120 is at the bottom of the figure and gp41 is at the top.