Figure 6. T42A-dependent changes in the activation of full-length SHP2.

(A) SHP2 activation is measured by incubation with phosphopeptide ligands, followed by monitoring dephosphorylation of the small-molecule substrate DiFMUP to generate fluorescent DiFMU. (B) Representative activation curves for SHP2^WT, highlighting peptide-dependent changes in EC₅₀ and amplitude. (C) Correlation between the EC₅₀ of SHP2^WT activation by phosphopeptides and the ${\mathrm{K}}_{\mathrm{D}}$ of those phosphopeptides for the N-SH2^WT domain. (D) Correlation between activation EC₅₀ values for SHP2^WT and SHP2^R138Q, which has weakened C-SH2 binding capacity. (E) Comparison of SHP2^WT and SHP2^T42A activation curves for the PD-1 pTyr 248 peptide, highlighting a significant impact on both EC₅₀ and amplitude. (F) Comparison of SHP2^WT and SHP2^T42A activation curves for the Imhof-9 peptide, highlighting a minor change in EC₅₀ and amplitude. (G) Bubble plot juxtaposing the EC₅₀ values for activation of SHP2^WT and SHP2^T42A by nine peptides, alongside the fold-change in ${\mathrm{K}}_{\mathrm{D}}$ for binding of those peptides to N-SH2^WT vs N-SH2^T42A. The dotted line indicates where EC₅₀ values would be equivalent for SHP2^WT and SHP2^T42A. The graph shows that peptides with a large fold-change in binding affinity (larger bubble) have a large fold-change in EC₅₀ values for SHP2^T42A over SHP2^WT (distance from dotted line). All EC₅₀ values can be found in Table S5.