| Assay Method Information | |
| | Bioassay |
| Description: | The IC50 of each compound shown in Table was with respect to the kappa opioid receptor was determined. The cell line for the OPRK1 antagonist assay stably expresses the following elements. The carboxy terminus of the OPRK1 receptor has a 7 amino acid linker, followed by the TEV protease cleavage site and a GAL4-VP16 fusion protein. The cell line also expresses a b-arrestin-2-TEV protease fusion protein and contains a reporter construct consisting of the UAS response element and the b-lactamase (bla) reporter gene. Upon activation of the receptor, g-protein receptor kinase (GRK) phosphorylates specific intracellular residues of OPKR1 and this induces recruitment of B-arrestin2-TEV protease fusion protein. The TEV protease recognizes and cleaves the TEV site, releasing the GAL4-VP16 fusion protein, which then translocates to the nucleus. The GAL4-V16 binds to the UAS element, driving expressing of the b-lactamase gene. B-lactamase expression is detected with the cell permeable, fluorescent substrate, CCF4-AM. This substrate consists of coumarin tethered to fluoroscein via a b-lactam ring. In the absence of b-lactamase, excitation of the dye with 405 nm light results in FRET from the coumarin to fluoroscein and emission of green (525 nm maximum) light. B-lactamase cleavage of the substrate separates the courmarin fluorophore from the fluorscein, and 405 nm excitation results in blue (460 nm maximum) emission. |
| Affinity data for this assay | |
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