Assay Method Information

Assay Name:  Competition Binding Assay
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 μg/mL Hygromycin. GPR139 receptor expression was induced for 18 hrs with 1 μg/mL doxycycline (Sigma D9891) in growth media. After addition of doxycycline, cells were harvested in PBS and pelleted by centrifugation for 5 minutes at 200×G. Liquid was aspirated off and cells were resuspended in ice cold Lysis buffer (20 mM HEPES/5 mM EDTA pH 7.4/1× 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 2000×G 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.
Affinity data for this assay
 

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