Assay Report Card

ID: ALA3889212

Type: Binding

Description: Scintillation Proximity Assay (SPA): The binding of potential ligands to RORγ is measured by competition with [3H] 25-hydroxycholesterol (Perkin Elmer NET674250UC) using a scintillation proximity assay (SPA) binding assay. The ligand binding domain of human RORγ (A262-S507) with an N-terminal His tag is expressed in E. coli and purified using nickel affinity chromatography. 15 ug/well RORγ (A262-S507) is incubated with test compound at varying concentrations in 3-fold serial dilution, with final concentrations ranging from 16.6 uM to 0.28 nM for 10 min at room temperature in PBS buffer (Invitrogen #14190-144) containing 0.5% fatty acid free BSA (Gemini Bio-Products, Cat. #700-107P) and 0.1% Glycerol (Sigma Cat#G5516). 10 nM of [3H] 25-hydroxycholesterol is then added, and the reaction is incubated for 10 min. 10 mg/mL of Copper-His Tag-PVT beads (Perkin Elmer cat #RPNQ0095) are added, and the mixture is incubated for 60 min. The reaction is read on a TopCount Microplate scintillation plate reader (Perkin Elmer). The competition data of the test compound over a range of concentrations was plotted as percentage inhibition of radioligand specifically bound in the absence of test compound (percent of total signal). After correcting for non-specific binding, IC50 values were determined. The IC50 value is defined as the concentration of test compound needed to reduce [3H] 25-hydroxycholesterol specific binding by 50% and is calculated using the four parameter logistic equation to fit the normalized data.