Assay Method Information

Assay Name:  Assay of Co-Activator Recruitment by TR-FRET
Description:  The activity of compound of the invention can be determined by a co-activator recruitment by TR-FRET (time-resolved fluorescence resonance energy transfer) assay. In general, the assay is based on the interaction between N-terminally Six-Histidine-tagged-RORC2 ligand binding domain (6-His-RORC2 LBD), expressed in E. coli and purified by affinity chromatography, and biotin-coactivator peptide SRC1-2 (biotin-aminohexanoic acid-CPSSHSSLTERHKILHRLLQEGSPS-NH2; SEQ ID NO: 1) containing the LXXLL (SEQ ID NO: 2) consensus domain which is responsible for receptor binding. This interaction is detected by addition of Europium labeled-anti-His antibody (Ex. 337 nm, Em. 620 nm, which binds to 6His) and Streptavidin-APC (Ex. 620 nm, Em. 665 nm, which binds to biotin). When receptor and coactivator are bound to each other, upon shining light at 337 nm on the sample, the Europium emits fluorescence that excites APC due to close proximity (FRET) and this signal is measured at 665 nm. Due to the long lasting fluorescence emission of Europium, the non-specific, short-lived fluorescence is time-resolved (TR) from the fluorescence of interest. Inhibitors of the interaction of receptor and coactivator peptide are detected by a decrease in TR-FRET signal.Specifically, in one embodiment the aforementioned assay was performed as outlined below. The assay was carried out in black polystyrene, 384-well plates in a total assay volume of 50.5 μL. The assay buffer contained 50 mM TRIS-HCL pH 7.5, 1 mM NaCl, 2 mM MgCl2, 0.5 mg/mL bovine serum albumin, and 5 mM dithiothreitol. The final concentration of reagents was 6.3 nM RORC2 LBD, 200 nM SRC1-2, 50 nM streptavidin APC, 1 nM Europium-labeled anti-His antibody, and varying concentrations of compounds such that final concentration of DMSO is 1% (v/v). The assay steps were: (1) dispensing 500 μL compound at 100× final concentration in DMSO (test wells) or DMSO only (control wells for no inhibition); and (2) dispensing 50 μL mixture of the other assay components including receptor (test wells) or excluding receptor (control wells for maximal inhibition).Assay mixtures were incubated are room temperature for 3 hr and read in EnVision 2100 Multilabel Reader (PerkinElmer Life Sciences) at Excitation Filter 320, Emission Europium Filter 615, Emission APC Filter 665, Dichroic Mirror D400/D630.
Affinity data for this assay
 

If you find an error in this entry please send us an E-mail