Figure 2.

IC₅₀ values for Src and Fes-SH2 variants binding to phosphopeptides. Schema depicting the different Src-derived and Fes-derived sequences grafted into the (a) Src-SH2 domain or (b) Fes-SH2 domain. Binding to pTyr-peptide pMT (sequence: EEPQpTyrEEIPIY) or pTyr-peptide pEZ (sequence: PPPVpTyrEPVSYH) for Src or Fes variants, respectively, was assayed by competitive SH2 phage ELISAs. The IC₅₀ value was derived from the binding curves, and the fold change relative to the IC₅₀ for the wt domain was calculated. Data are an average of 3 to 4 experimental replicates ± SEM. Sequences derived from Src or Fes are colored pink or blue, respectively, and light or dark colors indicate wt or superbinder sequences, respectively. “NDI” indicates “no detectable inhibition”.