CHEMBL5730396

Radioligand Binding Assay: An in vitro binding assay was used to determine the compound Ki value or ability to antagonize binding of a peptide agonist to the human melanin concentrating hormone receptor (MCHR1). Membranes from stably transfected HEK-293 cells expressing a mutated (E4Q, A5T) hMCHR1 receptor were prepared by dounce homogenization and differential centrifugation. Binding experiments were carried out with 0.5-1.0 ug of membrane protein incubated in a total of 0.2 mL in 25 mM HEPES (pH 7.4) with 10 mM MgCl2, 2 mM EGTA, and 0.1% BSA (Binding Buffer) for 90 min. For competition binding assays, reactions were carried out in the presence of with 0.06-0.1 nM [Phe13, [125I]Tyr19]-MCH and increasing concentrations of unlabeled test molecules. Reactions were terminated by rapid vacuum filtration over 96 well-GFC UNIFILTER plates pre-coated with 0.075 mL binding buffer containing 1% BSA, and washed 3 times with 0.4 mL of Phospho-buffered Saline (pH 7.4) containing 0.01% TX-100. Filters were dried, 0.05 mL MicroScint 20 was added to each well and radioactivity was subsequently quantified by scintillation counting on a TOPCOUNT microplate scintillation counter (Packard). Inhibitory constants were determined by nonlinear least squares analysis using a four parameter logistic equation.