Assay Method Information

Assay Name:  Inhibition Assay
Description:  The assay is based on the principle that binding of the agonist to the RORγ causes a conformational change around helix 12 in the ligand binding domain, resulting in higher affinity for the co-activator peptide. The Fluorescein-D22 co-activator peptide used in the assay is recruited in the absence of a ligand. Binding of the co-activator peptide, causes an increase in the TR-FRET signal while binding of an inhibitor decreases the recruitment of the co-activator peptide, causing a decrease in the TR-FRET signal compared to a control with no test compound. The assay was performed using a two-step procedure, pre-incubation step with the test compound followed by the detection step on addition of the anti-GST tagged terbium (Tb) and fluorescein tagged fluorophores as the acceptor.Test compounds or reference compounds such as T0901317 (Calbiochem) were dissolved in dimethylsulfoxide (DMSO) to prepare 10.0 mM stock solutions and diluted to the desired concentration. The final concentration of DMSO in the reaction was 4% (v/v). The assay mixture was prepared by mixing 10 nM of the GST-tagged ROR gamma ligand binding domain (LBD) in the assay buffer containing 25 mM HEPES (pH 7.4), 100 mM NaCl, 5 mM DTT and 0.01% BSA with or without the desired concentration of the test compound. The reaction was incubated at 22° C. for 1 hour. The pre-incubation step was terminated by addition of the detection mixture containing 300 nM Fluorescein-D22 co-activator peptide and 10 nM lantha screen Tb-anti GST antibody into the reaction mixture. After shaking for 5 minutes the reaction was further incubated for 1 hour at room temperature and read at 4° C. on an Infinite F500 reader as per the kit instructions (Invitrogen).
Affinity data for this assay
 

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