Kinase experiment:

The kinase binding assay is used to assess compound binding to TTK by monitoring displacement of a fluorescently labeled, ATP site-directed kinase inhibitor (Kinase Tracer 236) from the kinase active site. Each 15 μL assay contains 5 nM TTK, variable amounts of test compound (Mps1-IN-2), 30 nM Kinase Tracer 236, 2 nM Eu-anti-GST Antibody, and 1% DMSO (residual from compound dilution) in Kinase Buffer A (50 mM HEPES pH 7.5, 10 mM MgCl2, 1 mM EGTA, 0.01% Brij-35). Binding assays are initiated by addition of 5 μL of test compound (from 2-fold dilution series) to 5 μL of a kinase/antibody mixture, followed by addition of 5 μL of antibody. Assay plates are read using using standard Eu-based TR-FRET settings with excitation at 340 nm and emission monitored at 615 nm (donor) and 665 nm (acceptor). Emission intensities are measured over a 200 μs window following a 100 μs post-excitation delay[1].

Mps1-IN-2 is a potent and selective ATP-competitive inhibitor of Mps1 kinase with the IC50 value of 145nM [1].

Mps1-IN-2 has been reported to inhibit Mps1 kinase activity with the IC50 value of 145nM, when screened at 1μM ATP. In addition, Mps1-IN-2 has shown greater than 1000-fold selectivity to the Alk and Ltk enzyme. Moreover, Mps1-IN-2 has been revealed to bound to the ATP biding pocket of Mpa1 and formed a hydrogen bond with the hinge backbone (Glu603) at 2.74-A resolution. Mps1-IN-2 has been noted to abrogate SAC function and override the checkpoint through direct inhibition of Mps1[1].

References:
[1] Kwiatkowski N1, Jelluma N, Filippakopoulos P, Soundararajan M, Manak MS, Kwon M, Choi HG, Sim T, Deveraux QL, Rottmann S, Pellman D, Shah JV, Kops GJ, Knapp S, Gray NS. Small-molecule kinase inhibitors provide insight into Mps1 cell cycle function. Nat Chem Biol. 2010 May;6(5):359-68. doi: 10.1038/nchembio.345. Epub 2010 Apr 11.