Fluorescence Polarization Screening Assays for Small Molecule Allosteric Modulators of ABL Kinase Function
A) A library of 1200 FDA-approved compounds was screened using the ABL N32L protein (25 μg/well) and the p41 probe peptide (50 nM) in the FP assay. The solid lines correspond to the mean FP signals for the wild type (WT) and SH3 mutant (W118A) control N32L proteins across all assay plates, with the dotted lines indicating three standard deviations from the means (± 3σ). Compounds were screened at 10 μM and each FP signal is represented as an individual circle. Five putative hit compounds were identified (green circles). B) The five potential hit compounds were re-tested in quadruplicate at 10 μM vs. the DMSO control under FP screening assay conditions, and the mean FP values are shown ± SE. Four of these compounds significantly inhibited the FP signal relative to the DMSO control as indicated by the asterisk (p < 0.05; 2-tailed t-test). The dotted line shows the FP value three standard deviations below the DMSO control FP signal (-3σ).