Figure 5. Differential sensitivity of individual SFK-YEEI proteins to activation by SH3 domain displacement.

Each of the SFK-YEEI proteins shown was assayed in the presence of VSL12 over a range of concentrations (0.1 to 300 µM). ATP and substrate concentrations were set to the K_m for each kinase, and input kinase concentrations were set to achieve a basal reaction velocity of 1 pmol ADP produced/min. A) Each of the kinases is activated by VSL12 in a concentration-dependent manner. Plots of reaction velocity vs. VSL12 concentration were best-fit by the Michaelis-Menten equation, allowing for the determination of the V_max. Each data point was assayed in triplicate and is shown as the mean ±S.E. B) Comparison of basal rate (left) and V_max (right) for each kinase in the presence of VSL12. Bars heights correspond to the mean values from triplicate experiments ±S.E.