We found striking differences in the potency of inhibitors when assessed in vitro versus in live cells - mostly due to differences in protein expression construct used, activation state of the protein, concentration of natural competitors (e.g. ATP) and post-translational modifications present. Therefore, we found it to be crutial to assess inhibitor binding in living cells. The method of our choice is called NanoBRET and was invented by Promega. The technique uses living HEK293T cells for a transient expression of a full-length protein kinase fused to a NanoLuciferase - that emits light upon substrate addition. In the NanoBRET assay we see a competition between a flourescently used tracer molecule and your molecule of interest - resulting in a dose-dependant decrease in Bioluminescence Resonance Energy Transfer. Becasue we use living human cells, we address the problems mentioned above: We assess the binding of your inhibitor to a full-length protein with human Post translational modifications surrounded by a cell membrane and all natural substrates (e.g. 1 mM ATP) and other binding partners that may affect the activation state. We want to speed up your drug discovery project by quickly and accurately characterizing your small molecule inhibitor across the kinome in living cells using the NanoBRET technology. Please visit our website and/or contact us for more info! Let’s illuminate science together!