CHEMBL5735378

Radioligand Binding Assays: Receptor 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.