| Assay Method Information | |
| | PI3Kdelta Scintillation Proximity Assay |
| Description: | [γ-33P]ATP (10 mCi/mL) was purchased from PerkinElmer (Waltham, Mass.). Lipid kinase substrate, D-myo-Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)D (+)-sn-1,2-di-O-octanoylglyceryl, 3-O-phospho linked (PIP2), CAS 204858-53-7, was purchased from Echelon Biosciences (Salt Lake City, Utah). PI3Kδ (p110δ/p85α) was purchased from Millipore (Bedford, Mass.). ATP, MgCl2, DTT, EDTA, MOPS and CHAPS were purchased from SigmaAldrich (St. Louis, Mo.). Wheat Germ Agglutinin (WGA) YSi SPA Scintillation Beads was purchased from GE healthcare life sciences (Piscataway, N.J.). The kinase reaction was conducted in polystyrene 384-well matrix white plate from Thermo Fisher Scientific in a final volume of 25 μL. Inhibitors were first diluted serially in DMSO and added to the plate wells before the addition of other reaction components. The final concentration of DMSO in the assay was 0.5%. The PI3K assays were carried out at room temperature in 20 mM MOPS, pH 6.7, 10 mM MgCl2, 5 mM DTT and CHAPS 0.03%. Reactions were initiated by the addition of ATP, the final reaction mixture consisted of 20 μM PIP2, 20 μM ATP, 0.2 μCi [γ-33P] ATP, 4 nM PI3Kδ. Reactions were incubated for 210 min and terminated by the addition of 40 μL SPA beads suspended in quench buffer: 150 mM potassium phosphate pH 8.0, 20% glycerol. 25 mM EDTA, 400 μM ATP. The final concentration of SPA beads was 1.0 mg/mL. After the plate sealing, plates were shaken overnight at room temperature and centrifuged at 1800 rpm for 10 minutes, the radioactivity of the product was determined by scintillation counting on Topcount (PerkinElmer). IC50 determination was performed by fitting the curve of percent control activity versus the log of the inhibitor concentration using the GraphPad Prism 3.0 software. |
| Affinity data for this assay | |
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