| Assay Method Information | |
| | Detection of the Antagonism of the Human Prostaglandin D Receptor Signal |
| Description: | 5. 1 Detection PrincipleBinding of prostaglandin D2 to the human PGD receptor induces activation of membrane-bound adenylate cyclases and leads to the formation of cAMP. In the presence of the phosphodiesterase inhibitor IBMX, the cAMP which has accumulated as a result of this stimulation and is released by cell lysis is employed in a competitive detection method. In this test, the cAMP present in the lysate competes with a fluorescently labelled cAMP (cAMP-d2) for binding to an anti-cAMP antibody labelled with an Eu cryptate.The absence of cellular cAMP leads to a maximum signal owing to this cAMP-d2 molecule binding to the antibody. Excitation of the cAMP-d2 molecule at 337 nm leads to a fluorescence resonance energy transfer (FRET) to the Eu cryptate molecules of the anti-cAMP antibody (labelled therewith), followed by a long-lasting emission signal at 665 nm (and also at 620 nM). The two signals are measured in a suitable measuring device in a time-resolved manner, i.e. once the background fluorescence has subsided. Any increase of the low FRET signal owing to prostglandin E2 administration (measured as change in the well ratio=emission665nm/emission620nm*10 000) indicates the action of antagonists.5.2. Detection Method5.2.1. Test for Antagonism (Figures Per Well of a 384-Well Plate):4 μl of a cAMP-d2/cell suspension (625 000 cells/ml) were added to a test plate with the substance solutions (0.05 μl; 100% DMSO, concentration range 0.8 nM-16.5 μM) already charged. After 20 minutes of pre-incubation at room temperature (RT), 2 μl of a 3×PGD2 solution (6 nM, in PBS-IBMX) were added and the mixture was incubated in the presence of the agonist for a further 30 min at RT (volume: 6 μl). The reaction was then stopped by addition of 2 μl of lysis buffer and the mixture was incubated at RT for a further 20 min prior to the actual measurement (volume: 8 μl). |
| Affinity data for this assay | |
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