Figure 1. The structure of the Grb2 SH2 domain in complex with a CD28-derived peptide.

(A) The overall structure. Grb2 SH2 is shown as a cartoon model, whereas the peptide is shown as a stick model. (B) The interactions between the phosphotyrosine, pTyr191^pep, and the SH2 domain. The main-chain trace of the SH2 domain is shown as blue tubes with the side-chains of some key residues in thin sticks. The phosphopeptides are shown as thick stick models. The green dashed lines indicate hydrogen bonds. (C) The interactions between the conserved asparagine, Asn193^pep, of the peptide (thick sticks) and the SH2 domain (thin sticks).