Assay Report Card

ID: ALA3888355

Type: Binding

Description: Inhibition Assay: PI3 kinases catalyse the phosphorylation of phosphatidylinositol 4,5-biphosphate (PIP2) to phosphatidylinositol 3,4,5-triphosphate (PIP3) in the presence of ATP and Mg2+ ions. The PIP3 product can be detected by displacement of biotin-PIP3 from energy transfer complexes consisting of europium labelled anti-GST monoclonal antibody, a GST-tagged Pleckstrin homology (PH) domain, biotinylated PIP3 and streptavidin-allophycocyanin (APC) by the time-resolved fluorescence resonance energy transfer (TR-FRET) (HTRF® PI3K enzyme assay, Millipore). Excitation (330 nm) of europium in the complex results in an energy transfer to the APC and a fluorescent emission at 665 nm although europium itself emits at its characteristic 620 nm. The PIP3 product formed by PI3K activity displaces biotin-PIP3 from the complex and results in a loss of energy transfer (decreasing signal). The compound to be tested was added, at the desired final concentrations, to a mixture of PIP2 substrate and recombinant PI3 kinase α, δ or γ enzymes (Millipore), and the mixture incubated for 2 hr at RT. Following this incubation period, ATP (20 μM) was added to the enzyme/compound/PIP2 substrate mixture and the resulting mixture was incubated for 30 min at RT. A stopping solution containing biotinylated PIP3 and the detection mix containing the GST tagged GRP1 pleckstrin homology (PH) domain and fluorophores were then added and the mixture was incubated at RT for 15-18 hr, prior to detection in a fluorescence microplate reader (Varioskan® Flash, ThermoFisher Scientific).

Organism: Homo sapiens