Skip to main content
. Author manuscript; available in PMC: 2018 Jul 6.
Published in final edited form as: Annu Rev Immunol. 2016 May 20;34:635–659. doi: 10.1146/annurev-immunol-041015-055515

Figure 2.

Figure 2

Structure of the HIV envelope spike. In a crystal structure of the HIV strain BG505 expressed as SOSIP.664 near-native trimers [PDB 4zmj (31)], the location of some of the most important Env trimer domains is indicated as viewed (a) from the side or (b) from the top. The gp120 subunits form the blades of a propeller-like structure, whereas the gp41 subunit forms a central stalk and a membrane-proximal, pedestal-like structure. As predicted from other experimental data, hypervariable loops V1 through V3 are located at the apex of the trimer, with hypervariable loop V3 being partially buried under hypervariable loops V1 and V2. These loops are also in proximity to the CD4 receptor binding site that is recessed left in the cleft formed by two propeller blades. Loops that did not resolve in the structure are indicated by a dashed line.