| Assay Method Information | |
| | Biochemical Assay |
| Description: | This assay was developed and further optimized from a kit produced by Upstate (Millipore catalog #33-047) (Millipore Sigma, Billerica Mass., USA) and has been configured for high throughput screening (HTS) and structure-activity relationship (SAR) screening. Briefly, this procedure exploits the exquisite specificity and high affinity binding of enzyme reaction substrate phosphatidyl(3,4,5)triphosphate (PIP3) to the GRP1 pleckstrin homology (PH) domain to generate the signal. In the absence of PIP3, an HTRF (Homogeneous Time-Resolved Fluorescence energy transfer) complex is formed consisting of europium (u)-labeled anti-GST, GST tagged GRP1-PH domain, biotin-PIP3 (biotinylated-PIP3) and streptavidin conjugated APC (Allophycocyanin). The native PIP3 produced by PI3-Kinase activity disrupts in a competitive manner the biotin-PIP3 from the pleckstrin homology (PH) domain, resulting in the loss of energy transfer (HTRF complex) and a decrease in the signal. The format of this assay is the same for all 4 isoforms of PI3K; the differences lie in the concentration of enzyme used to achieve robust assay window. The alpha, beta, and delta assays are run at 0.5, 1, and 0.3 nM enzymes and the gamma assay is run at 5 nM enzyme. The ATP concentration is 100 uM in the alpha, beta, and delta assays and 50 uM adenosine triphosphate (ATP) in the gamma assay. All reactions are run at 5 uM PIP2. |
| Affinity data for this assay | |
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