| Assay Method Information | |
| | Radioligand Binding Assay on Rat |
| Description: | HEK-293 cells stably expressing rat TAAR1 were maintained at 37° C. and 5% CO2 in DMEM high glucose medium, containing fetal calf serum (10%, heat inactivated for 30 min at 56° C.), penicillin/streptomycin (1%), and 375 μg/ml geneticin (Gibco). Cells were released from culture flasks using trypsin/EDTA, harvested, washed twice with ice-cold PBS (without Ca2+ and Mg2+), pelleted at 1,000 rpm for 5 min at 4° C., frozen and stored at −80° C. Frozen pellets were suspended in 20 ml HEPES-NaOH (20 mM, pH 7.4) containing 10 mM EDTA and homogenized with a Polytron (PT 6000, Kinematica) at 14,000 rpm for 20 s. The homogenate was centrifuged at 48,000×g for 30 min at 4° C. Subsequently, the supernatant was removed and discarded, and the pellet resuspended in 20 ml HEPES-NaOH (20 mM, pH 7.4) containing 0.1 mM EDTA using the Polytron (20 s at 14,000 rpm). This procedure was repeated and the final pellet resuspended in HEPES-NaOH containing 0.1 mM EDTA and homogenized using the Polytron. Typically, aliquots of 2 ml membrane portions were stored at −80° C. With each new membrane batch the dissociation constant (Kd) was determined via a saturation curve. The TAAR1 radioligand 3[H]-(S)-4-[(ethyl-phenyl-amino)-methyl]-4,5-dihydro-oxazol-2-ylamine (described in WO 2008/098857) was used at a concentration equal to the calculated Kd value, that was usually around 2.3 nM, resulting in the binding of approximately 0.2% of the radioligand and a specific binding representing approximately 85% of the total binding. Nonspecific binding was defined as the amount of 3[H]-(S)-4-[(ethyl-phenyl-amino)-methyl]-4,5-dihydro-oxazol-2-ylamine bound in the presence of 10 μM unlabeled ligand. All compounds were tested at a broad range of concentrations (10 μM to 10 μM) in duplicates. The test compounds (20 □μl/well) were transferred into a 96 deep well plate (TreffLab), and 180 μl of HEPES-NaOH (20 mM, pH 7.4) containing MgCl2 (10 mM) and CaCl2 (2 mM) (binding buffer), 300 μl of the radioligand 3[H]-(S)-4-[(ethyl-phenyl-amino)-methyl]-4,5-dihydro-oxazol-2-ylamine at a concentration of 3.3×Kd in nM and 500 μl of the membranes (resuspended at 50 μg protein per ml) added. |
| Affinity data for this assay | |
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