| Assay Method Information | |
| | YO-PRO-1 Uptake Assay |
| Description: | YO-PRO -1 is a fluorescent DNA-binding dye with a MW of 374 Da (Molecular Probes, cat. Y3603). This method is based upon the presumed ability of YO-PRO-1 to enter through the dilated or "large pore form" of P2X7 receptor and to bind to intracellular DNA whereupon it increases many fold its fluorescence intensity. The dye has an absorption spectrum compatible with excitation at 488 nm by argon laser sources and its emission wavelength is in the range of 515-575 nm. The aim of this assay was to validate the interaction of antagonists with P2X7 receptor using an alternative readout to Ca2+-sensitive fluorescent dyes.HEK-293 cells stably transfected with P2X7 receptor were seeded overnight in growth medium at 20,000 cells/well in 384-well plate. 24 hours later, the medium was removed, the cells were washed with Low Divalent Cation Assay Buffer (0.3 mM Ca2+ and 0 mM Mg2+) and then pre-loaded with 20 μL/w of 5 μM YO-PRO -1 dye. FLIPRTETRA fluorescence measurement immediately started. Then, 10 μL/w of test compounds and reference antagonist A438079 at 3×-concentration were injected with the FLIPRTETRA and the kinetic response over a period of five minutes was monitored. A second injection of 10 μL/w of 3× Bz-ATP EC80 (30 μM) was performed with the FLIPRTETRA and the signal of the emitted fluorescence was recorded for additional 60 minutes. All the experiment was carried out with a Low Divalent Cation Assay Buffer (0.3 mM Ca2+ and 0 mM Mg2+).The effect of the test compounds was measured as percent inhibition vs the reference antagonist and IC50 values were calculated accordingly. |
| Affinity data for this assay | |
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