Assay Method Information

Assay Name:  Lanthascreen Kinase Binding Assay for mTOR (G)
Description:  Binding Assays are based on the binding and displacement of an Alexa Fluor 647-labeled, ATP-competitive kinase inhibitors to the kinase of interest. Invitrogen's Kinase Tracers have been developed to address a wide range of kinase targets and are based on ATP-competitive kinase inhibitors, making them suitable for detection of any compounds that bind to the ATP site or to an allosteric site altering the conformation of the ATP site.In the Lanthascreen kinase binding assay, the donor (Eu3+-anti-GST (glutathione S-transferase) antibody) is excited at 340 nm and will transfer its energy to the acceptor (Alexa Fluor 647-labeled ATP-competitive kinase inhibitor=Tracer-314). The emission from the Tracer-314 (Alexa Fluor 647 inhibitor) can be monitored with a filter centered at 665 nm because it is located between the emission peaks of the donor, which is measured at 615/620 nm. The binding of both, the Tracer-314 and Eu3+-anti-GST antibody, to the kinase results in a high degree of FRET from the Eu3+-donor fluorophore to the Alexa-Fluor 647-acceptor fluorophore on the Tracer-314. Binding of an inhibitor to the kinase competes for binding with the tracer, resulting in a loss of FRET.50 nL of compound dilutions were dispensed onto white 384-well small volume polystyrene plate. Then 5 ul of GST-mTOR and Europium-anti-GST antibody followed by 5 ul of tracer-314 (final assay volume 10 ul) are incubated at RT. The standard reaction buffer for the Lanthascreen kinase binding assay contained 50 mM HEPES pH 7.5, 5 mM MgCl2, 1 mM EGTA, 0.01% Pluronic F-127. Plates are read 60 mins later in a Synergy2 reader using an integration time of 0.2 microseconds and a delay of 0.1 microseconds.To calculate the emission ratio, the signal emitted at 665 nm from the acceptor (Alexa Fluor 647-labeled Tracer-314) is divided by the signal emitted at 620 nm from the donor (Eu3+ anti-GST antibody).Control for the 0% inhibition was given by the solvent vehicle of the compounds (90% DMSO in H2O). Control for the relative 100% inhibition was performed by adding 10 uM in the mix containing GST-mTOR and Europium anti-GST antibody. An additional control for the absolute 0% inhibition is given by Eu3+ anti-GST antibody without GST-mTOR. Standard compounds for the lipid kinase panel profiling were used as a reference and included in all assay plates in the form of 8 dilution points.
Affinity data for this assay
 

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