Figure 3.

Phosphorylation of Tyr¹⁵¹⁰ of IQGAP1 creates a docking site for SH2 domains. (A). A peptide array containing 124 different GST-tagged recombinant SH2 protein domains, each spotted in duplicate, was generated as detailed in Materials and Methods. GST alone was spotted on the array as the negative control. Biotinylated peptides comprising residues 1502–1518 of IQGAP1 with phosphorylated Tyr¹⁵¹⁰ (pTyr¹⁵¹⁰) were labeled with fluorescent streptavidin and incubated with the array for 16 h at 4 °C. After washing, fluorescence from the bound peptides (green dots) was detected. The red and orange circles delineate the duplicates for the SH2 domains of Abl1 and Abl2, respectively. (B). Similar analysis was conducted with the same IQGAP1 peptide, except Tyr¹⁵¹⁰ was not phosphorylated. (C). The peptide array was probed with anti-GST antibody to show the positions and loading of the GST-SH2 domains and control GST.