Figure 7 - full size

Figure 7.
Figure 7 A model for interaction of SDF-1 with CXCR4. A schematic depicting the interaction of SDF-1 with the receptor is shown. CXCR4 is shown with the seven helices represented as cylinders, which are connected by the surface and cytoplasmic loops. The N-terminal and C-terminal segments of the receptor, and the N- and C-terminus of SDF-1, are annotated as N and C. SDF-1 is shown as a MOLSCRIPT diagram. (A) indicates the receptor and ligand separately prior to any interaction between the two. (B) indicates interaction of the SDF-1 RFFESH loop (site 1) with the N-terminal segment of the receptor. The contact region is shown in blue. Two of the helices are truncated [compare with (A)] to highlight the binding groove of the receptor. (C) Shows the N-terminal region (site 2) of SDF-1 bound in groove at the top of the helices (orange). Binding of the N-terminal region results in activation of the receptor, which is depicted in (C) by the change in conformation of the receptor helices compared with (B).