FIG. 2.

Binding of soluble gp120 proteins to peptide variants of XD3 on peptide arrays. (A and B) Peptides are numbered 1 to 16, and their sequences are shown in panel C (sulfated tyrosines are in lowercase and boldface type). Binding of the indicated His-tagged gp120 proteins, both in the presence (+) and the absence (−) of sCD4, was detected with an HRP-conjugated anti-His MAb and visualized by chemiluminescence. The lower panels are controls showing the background reactivity of the anti-His MAb with some peptides in the presence of sCD4 and the strong reactivity of the sulfated peptides with MAb 1C-A12. (B) Longer exposure times (5 times) have been used to visualize binding of R5 Env to the peptides.