FIG. 9.

Summary of binding determinants on CXCR4 for VCP and ROD/B gp120s. A sequence alignment of extracellular regions in human, rat, and feline CXCR4 is shown. The first, second, and third extracellular loops are referred to as ECL1, ECL2, and ECL3, respectively. Binding sites identified in this study are shown for VCP gp120 (solid rectangles) and ROD/B gp120 (hatched rectangles). Shaded rectanges, residues important for SDF-1α binding and signaling (9, 86); open rectangle, epitope for 12G5 (6, 10).