| Assay Method Information | |
| | Competition Binding |
| Description: | This membrane based assay measures the ability of compounds to competitively bind GPR139 in stably transfected CHO-TRex membranes. CHO-TRex (Life Technologies) cells were stably expressed with human GPR139 receptor, whose expression is controlled by a tetracycline inducible element. The cells were cultured in medium containing F12K, 10% Tetracycline free FBS, 1% Penn/Strep, 200 ug/mL Hygromycin. GPR139 receptor expression was induced for 18 hrs with 1 ug/mL doxycycline (Sigma D9891) in growth media. After addition of doxycycline, cells were harvested in PBS and pelleted by centrifugation for 5 minutes at 200xG. Liquid was aspirated off and cells were resuspended in ice cold Lysis buffer (20 mM HEPES/5 mM EDTA pH 7.4/1x Roche protease inhibitor). Samples were vortexed until homogenous and then placed on ice and homogenized using Dounce homogenizer on 50% power 3 separate times for 10 strokes each time. Lysate was centrifuged at 4° C. for 10 minutes in a tabletop Sorvall at 2000xG and supernatant was recovered and centrifuged in a Sorvall Ultracentrifuge at 35,000 rpm for 30 minutes at 4° C. The supernatant was discarded and the remaining pellet resuspended in Lysis buffer (20 mM HEPES/0.1 mM EGTA/Roche protease inhibitor). Membrane protein concentration was determined using ThermoFisher BCA quantification kit and aliquoted into microtubes. Tubes were snap frozen in LN2 and stored at -80° C.Membranes were removed from -80° C., thawed and diluted in cold radioligand assay buffer (20 mM HEPES pH 7.4/5 mM MgCl2/l mM CaCl2/Roche protease inhibitor). Compounds suspended in DMSO were diluted in 1 nM (S)-N-(1-(2-[3H]-4-methoxyphenyl)propan-2-yl)-2-(2,3-dimethyl-7-oxothieno[2,3-d]pyridazin-6(7H)-yl)acetamide, readily prepared from (S)-N-(1-(2-chloro-4-hydroxyphenyl)propan-2-yl)-2-(2,3-dimethyl-7-oxothieno[2,3-d]pyridazin-6(7H)-yl)acetamide (20 mM HEPES pH 7.4/5 mM MgCl2/l mM CaCl2/Roche protease inhibitor fresh/(S)-N-(1-(2-chloro-4-methoxyphenyl)propan-2-yl)-2-(2,3-dimethyl-7-oxothieno[2,3-d]pyridazin-6(7H)-yl)acetamide) in a 0.3 mL 96 well polypropylene assay plate (Fisher Scientific). Membranes (10 ug) were added to the assay plate, spun for 30 seconds at 300 rpm in a tabletop Eppendorf centrifuge, and then incubated at room temperature for 20 minutes. Filtermat A (Perkin Elmer No. 1450-421) is pre-soaked in 0.5% PEI (Sigma P3143) for 3 hours and dried at room temperature overnight. The contents of the assay plate were transferred to Filtermat A (Perkin Elmer No. 1450-421) using Tomtec harvester and washed 5 times with cold wash buffer (Tris-HCl pH 7.5). Filtermats were dried using a microwave oven and placed in sample bags (Perkin Elmer No. 1450-432) with scintillator sheets (Perkin Elmer No. 1450-411). Scintillator sheets were melted to filtermats using a heat block set to 65° C., placed in MicroBeta cartridges and read using the MicroBeta scintillation counter. |
| Affinity data for this assay | |
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