The binding site of the RGT peptide. (A) SH3 domain (rendered by electrostatic surface) complexed with the RGT peptide (shown in stick representation). (B) Enlarged view of the binding site. Hyphenated lines indicate the intermolecular hydrogen bonds. The SH3 domain is shown as a diagram, and the residues that are involved in direct contact are shown in stick representation. The label for the RGT peptide is colored in red.