Assay Method Information

Assay Name:  In Vitro ORL-1 Receptor Binding Assay
Description:  ORL-1 Receptor Binding Assay Procedures: Membranes from recombinant HEK-293 cells expressing the human opioid receptor-like receptor (ORL-1) (Receptor Biology) were prepared by lysing cells in ice-cold hypotonic buffer (2.5 mM MgCl2, 50 mM HEPES, pH 7.4) (10 mL/10 cm dish) followed by homogenization with a tissue grinder/Teflon pestle. Membranes were collected by centrifugation at 30,000×g for 15 min at 4° C. and pellets resuspended in hypotonic buffer to a final concentration 1-3 mg/mL. Protein concentrations were determined using the BioRad protein assay reagent with bovine serum albumen as a standard. Aliquots of the ORL-1 receptor membranes were stored at −80° C.Radioligand binding assays (screening and dose-displacement) used 0.1 nM [3H]-nociceptin (NEN; 87.7 Ci/mmole) with 10-20 μg membrane protein in a final volume of 500 μL binding buffer (10 mM MgCl2, 1 mM EDTA, 5% DMSO, 50 mM HEPES, pH 7.4). Non-specific binding was determined in the presence of 10 nM unlabeled nociceptin (American Peptide Company). All reactions were performed in 96-deep well polypropylene plates for 1 h at about 25° C. Binding reactions were terminated by rapid filtration onto 96-well Unifilter GF/C filter plates (Packard) presoaked in 0.5% polyethylenimine (Sigma-Aldrich). Harvesting was performed using a 96-well tissue harvester (Packard) followed by three filtration washes with 500 μL ice-cold binding buffer. Filter plates were subsequently dried at 50° C. for 2-3 hrs. Fifty μL/well scintillation cocktail (BetaScint; Wallac) was added and plates were counted in a Packard Top-Count for 1 min/well. The data from screening and dose-displacement experiments were analyzed using Microsoft Excel and the curve fitting functions in GraphPad PRISM , v. 3.0, respectively, or an in-house function for one-site competition curve-fitting.
Affinity data for this assay
 

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