| Assay Method Information | |
| | a time-resolved fluorescence resonance energy transfer (TR-FRET) assay |
| Description: | Class I PI3K isoforms were expressed and purified as heterodimeric recombinant proteins. All assay reagents and buffers for the TR-FRET assay were purchased from Millipore. PI3K isoforms were assayed under initial rate conditions in the presence of 25 mM Hepes (pH 7.4), and 2×Km ATP (75-500 μM), 2 μM PIP2, 5% glycerol, 5 mM MgCl2, 50 mM NaCl, 0.05% (v/v) Chaps, 1 mM dithiothreitol, and 1% (v/v) DMSO at the following concentrations for each isoform: PI3Kα, PI3Kβ, and PI3Kδ between 25 and 50 pM, and PI3Kγ at 2 nM. The compounds of Table 1 and Compound X, ((S)-2,4-diamino-6-((1-(5-chloro-4-oxo-3-phenyl-3,4-dihydroquinazolin-2-yl)ethyl)amino)pyrimidine-5-carbonitrile) were added to the assay solution and incubated for 30 minutes at 25° C. The reactions were terminated with a final concentration of 10 mM EDTA, 10 nM labeled-PIP3, and 35 nM Europium labeled GRP-1 detector protein before reading TR-FRET on an Envision plate reader (Ex: 340 nm; Em: 615/665 nm; 100 μs delay and 500 μs read window).The results were normalized based on positive (1 pM wortmanin) and negative (DMSO) controls, and the IC50 values for PI3K α, β, δ, and γ were calculated from the fit of the dose-response curves to a four-parameter equation. These assays generally produced results within 3-fold of the reported mean. |
| Affinity data for this assay | |
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