| Assay Method Information | |
| | Radioligand Binding Assays |
| Description: | Method description for binding assays with human Somatostatin receptors by use of CHO cell membranes expressing recombinant human SSTR1 or human SSTR2 or human SSTR3 or human SSTR4 or human SSTR5Receptor binding assays refer to a technique in which labeled receptor ligands are used to detect binding to a receptor. In competition experiments test compounds, which are not labeled, compete with the binding side of a labeled ligand. The displacement of the labeled ligand by the test compound leads to a decreased signal.Procedure:For the binding experiments 200 μL of membrane homogenate from one of the following protein amounts is used: hSSTR1 (40 μg/well); hSSTR2 (25 μg/well); hSSTR3 (1.5 μg/well); hSSTR4 (0.5 μg/well); hSSTR5 (25 μg/well). The homogenate is incubated with 0.05 nM of radioligand ([3-125I-Tyr]-Somatostatin-(1-14)) in addition to increasing concentrations of a test compound or vehicle (100% binding) in a total volume of 250 μL using a Hepes buffer (10 mM, EDTA 1 mM, MgCl2 5 mM, pH7.6, BSA 0.5%, Bacitracin 0.003%, DMSO 1% for 180 min at room temperature. The incubation is terminated by filtration with ice cold NaCl 0.9% through polyethyleneimine treated (0.3%) GF/B glass fiber filters using a cell harvester. The protein-bound radioactivity is measured in a suitable reader. The non-specific binding is defined as radioactivity bound in the presence of 1 μM Somatostatin-14 during the incubation period.The analysis of the concentration-binding curves is performed by computer-assisted nonlinear least square curve fitting method using the model of one receptor binding site. |
| Affinity data for this assay | |
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