Figure 1 - Structural schema of the proposed molecular interaction between viral gp120 and human CCR5.

The viral protein is taken from an X-ray structure³⁰, the human coreceptor is from a homology model³¹. No measured structures of gp120 in complex with any coreceptor have been published. The orientation of the molecules with respect to each other is derived from modeling studies³¹. The C atoms of the two residues at positions 11 and 25 of the V3-loop that are the basis of the 11/25 rule are represented by red balls.