| Assay Method Information | |
| | STING SPA Binding Assay |
| Description: | The assay was run in 1536-well plates in a total volume of 8 μL per well by adding 8 nM [3H]-2′3′-cGAMP and 40 nM biotin-STING protein in assay buffer [25 mM HEPES (Corning 25-060-C1) pH 7.5, 150 mM NaCl (Sigma S5150), 0.5 mg/mL BSA (Gibco 15260-037), 0.001% Tween-20 (Sigma P7949), molecular grade water (Corning 46-000-CM)]. Test compounds (80 nL) were added with an acoustic dispenser (EDC Biosystems) in 100% DMSO for a final assay concentration of 1% DMSO. Plates were centrifuged for 1 min and incubated for 60 min at room temperature. Finally, (2 μL) polystyrene streptavidin SPA beads (PerkinElmer RPNQ0306) were added and plates were sealed and centrifuged for 1 min at room temperature. Plates were dark adapted for 2 h and read on a ViewLux (Perkin Elmer) for 12 min per plate. A saturation binding curve for [3<H]-2′3′cGAMP showed a KD of 3.6±0.3 nM for binding to STING, comparable to reported values for the natural ligand (Zhang et al., Cyclic GMP-AMP containing mixed phosphodiester linkages is an endogenous high-affinity ligand for STING (Molecular Cell 2013 51(2):10.1016/j.molcel.2013.05.022.). |
| Affinity data for this assay | |
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