CHEMBL5731954

S1P1 Binding Assay: Membranes were prepared from CHO cells expressing human S1P1. Cells pellets (1×109 cells/pellet) were suspended in buffer containing 20 mM HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), pH 7.5, 50 mM NaCl, 2 mM EDTA (Ethylenediaminetetraacetic acid) and Protease Inhibitor cocktail (Roche), and disrupted on ice using the Polytron homogenizer. The homogenate was centrifuged at 20,000 rpm (48,000 g) and the supernatant was discarded. The membrane pellets were resuspended in buffer containing 50 mM HEPES, pH 7.5, 100 mM NaCl, 1 mM MgCl2, 2 mM EDTA and stored in aliquots at −80° C. after protein concentration determination. Membranes (2 μg/well) and 0.03 nM final concentration of 33P-S1P ligand (1 mCi/ml, Perkin elmer or American Radiolabeled Chemicals) diluted in assay buffer (50 mM HEPES, pH7.4, 5 mM MgCl2, 1 mM CaCl2, 0.5% fatty acid free BSA (bovine serum albumin), 1 mM NaF) were added to the compound plates (384 Falcon v-bottom plate (0.5 μl/well in a 11 point, 3-fold dilution). Binding was performed for 45 minutes at room temperature, terminated by collecting the membranes onto 384-well Millipore FB filter plates, and radioactivity was measured by TOPCOUNT®. The competition data of the test compounds over a range of concentrations was plotted as percentage inhibition of radioligand specific binding. The IC50 is defined as the concentration of competing ligand needed to reduce specific binding by 50%.