Assay Report Card

ID: ALA3889256

Type: Binding

Description: Biological Assay: TAK1-TAB1 Binding Inhibitory Potency: The ability of candidate compounds to interact with TAK1-TAB1 is quantitated by a competitive binding assay using the LanthaScreen technology developed by Life Technologies. This assay is based on the binding of a proprietary, Alexa Fluor 647-labeled, ATP-competitive kinase inhibitor (kinase tracer-236) to the TAK1-TAB1 construct in presence of a europium-conjugated antibody, resulting in a FRET (fluorescence resonance energy transfer) signal. Displacement of the kinase tracer by compound results in a lower emission ratio upon excitation of the europium chelate. Candidate compounds are designed as potential irreversible inhibitors of TAK1-TAB1, capable of ligating to an active site cysteine residue. The time dependent nature of irreversible inhibition is investigated by performing the binding assay with and without a pre-incubation of compound and TAK1-TAB1. An increase in potency in the pre-incubated assay suggests the candidate compound could b of 10 nM TAK1-TAB1, 2 nM Eu-anti-his antibody, and 100 nM kinase tracer-236 using a 384-well plate format. Background signal is defined in the absence of TAK1-TAB1 and uninhibited signal is defined in the presence of vehicle (2% DMSO) alone. Compounds were evaluated in an 11 point dose-response ranging from 20 uM to 0.34 nM. The binding assays are performed under two conditions to evaluate time dependence of inhibition. For the pre-incubation assay, TAK1-TAB1 and Eu-anti-his antibody are preincubated with compound or vehicle for two hours prior to the addition of kinase tracer. The non-preincubated assay is run in which TAK1-TAB1 and Eu-anti-his antibody are added to a mixture of compound and kinase tracer. IC50 values of compounds are determined using a 4 parameter logistical fit of emission ratio as a function of the concentration of compound.