| Assay Method Information | |
| | Radioligand Binding Assay |
| Description: | Binding assays were performed as described in [J. A. O'Brien et al. Mol Pharmacol., 2003, 64, 731-740] with slight modifications, including that a radioligand that binds to the methyl-5-(2-pyridinylethynyl)pyridine (MPEP) binding site was used in place of [3H]-MPEP. Briefly, after thawing, the membrane homogenates were resuspended in 50 mM Tris-HCl and 0.9% NaCl binding buffer at pH 7.4 to a final assay concentration of 20 g protein/well for radioligand filtration binding. Incubations included 5 nM radioligand, membranes and either buffer or varying concentrations of compound. Samples were incubated for 60 min at room temperature with shaking. Non-specific binding was defined with 10 μM cold MPEP when using the radioligand. After incubation, samples were filtered over a GF/C filter (presoaked in 0.25% polyethyleneimine (PEI)) and then washed 4 times using a Tomtec Harvester 96 Mach III cell harvester (Tomtec, Hamden, Conn.) with 0.5 mL ice-cold 50 mM Tris-HCl (pH 7.4). IC50 values were derived from the inhibition curve and Ki values were calculated according to the Cheng and Prusoff equation of Ki=IC50/(1+[L]/Kd) described in [Y. Cheng and W. H. Prusoff Biochem. Pharmacol. 1973, 22, 3099-3108] where [L] is the concentration of radioligand and Kd is its dissociation constant at the receptor, derived from the saturation isotherm. |
| Affinity data for this assay | |
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