| Assay Method Information | |
| | [3H]-Spiperone Binding Assay at hD2 Recombinant Receptor |
| Description: | CHO cells stably expressing human dopamine receptor type 2, long variant (hD2L), coupled to Gα16 protein (CHO-Gα16-hD2L) were re-suspended in 20 mM HEPES, 2 mM EDTA (pH 7.4), homogenised and centrifuged at 40,000 g (20 min, 4° C.). After re-suspension, homogenization and centrifugation as above, the final pellet was re-suspended in 20 mM HEPES, 100 mM NaCl, 10 mM MgCl2, 1 mM EDTA (pH 7.4) and aliquots were kept at −80° C. [3H]-Spiperone Binding experiments were performed in 96 deep-well polypropylene plates in 50 mM Tris/HCl, 120 mM NaCl, 5 mM KCl, 5 mM MgCl2 (pH 7.4). Compounds of invention were serially diluted in DMSO at 100 fold final concentrations in the assay (1% DMSO final in the assay). Displacement was performed in the presence of 0.08 nM [3H]-Spiperone. The reaction was initiated by the addition of membrane suspension (2 μg of protein for CHO-hD2 membranes) and lasted for 120 min at 23° C. in a final volume of 1000 μl. Non specific binding (NSB) was determined in the presence of 0.1 μM Spiperone. The binding reaction was stopped by rapid filtration through GF/B filterplates pre-soaked in 0.5% polyetylenimmine (PEI) using a Packard cell harvester. After washing with ice-cold 0.9% NaCl, the plate was left to dry before the addition of Microscint 20 (50 μl/well, PerkinElmer). Radioactivity was counted with a TopCount (PerkinElmer). Data were analysed by non-linear regression analysis using GraphPad Prism 5.0 (GraphPad Software) or XLfit Version 5.2.0.0 (Copyright 2006-2009 ID Business Solutions Ltd). Saturation binding experiments were performed similar to the competition binding experiments using a radioligand concentrations ranging from 0.011 to 3.0 nM. Ref: Durcan M. J. et al. (1995). Is Clozapine selective for the dopamine D4 receptor? Life Sciences, 57: 275-283. Petrus J. et al. (2001). Real-time analysis of dopamine: antagonist interactions at recombinant human D2long receptor upon modulation of its activation state. Brit. J. Pharmacol. 134, 88±97. |
| Affinity data for this assay | |
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