Lipid Kinase Assays: PI3K-Glo™ Class I Profiling Kit

Phosphatidylinositol (PI) and its phosphorylated derivates, collectively called phosphoinositides, are important second messengers that are critical as signaling molecules and for cellular membrane remodeling. These derivatives are generated by a family of kinases called phosphoinositide lipid kinases (PIKs). Nineteen PIK isoforms have been identified in mammals. Based on their ability to preferentially phosphorylate the hydroxyl group of the inositol ring on position 3, 4 or 5, they have been broadly classified into three major families: phosphoinositide 3-kinases (PI3Ks), phosphoinositide 4-kinases (PI4Ks) and phosphoinositide phosphate-kinases (PIP5Ks and PIP4Ks).

Promega lipid kinase enzymes, substrates and detection systems provide a complete set of reagents for performing phosphoinositide lipid kinase (PIK) reactions using a luminescent ADP-detection platform, the ADP-Glo™ Kinase Assay. The reagents include purified human recombinant proteins of Class I PI3Ks, optimized reaction buffer and ready-to-use lipid kinase substrates.

The PI3K-Glo™ Class I Profiling Kit contains PI3Ks (α, β, γ and δ; 5μg each), PIP2:3PS Lipid Kinase Substrate (0.25mg) and the ADP-Glo™ Kinase Assay, 1,000 assays. The lipid substrates are supplied as frozen small unilamellar vesicles containing a mixture of phosphatidylinositol (PI) or phosphoinositol-4,5-bisphosphate (PIP2) at a 1:3 ratio with phosphatidylserine (PS) as carrier lipid. The PIP2:3PS substrate is optimized for use with class I PI3Ks.  The PI:3PS substrate provides a universal PI lipid kinase substrate.

This easy-to-use luminescent assay provides sensitive detection with a high signal-to-background ratios even at low % conversion of substrate. The assay is easily scalable to 1,536-well format, reducing cost per well, and making it well-suited for screening applications.