Phosphatidylinositol 3-kinase (PI3-kinase) is a universal enzyme associated with receptor signaling pathways. It generates second messenger phospholipids by phosphorylating the D-3 position of inositol phospholipids including phosphatidylinositol (PI), PI-4-phosphate, and PI-4, 5-biphosphate. The enzyme exists as a heterodimer composed of regulatory 85 kDa (p85) and catalytic 110 kDa (p110) subunits. The p85 subunit contains two SH2 (src-homology 2) domains and an SH3 domain. The catalytic activity of the p110 subunit is stimulated when the p85 regulatory subunit binds, through its SH2 domains, to activated receptor and non-receptor tyrosine kinases. Two p85 isoforms have been described, p85a and p85ß. Both isoforms bind to activated receptors and each may be responsible for mediating a subset of PI3-kinase interactions.
Clone U15 recognizes the p85 regulatory subunit of PI3 kinase (p85α). It reacts with human, monkey, and cow PI3 kinase. It does not cross-react with mouse or rat PI3 kinase. Recombinant cow p85α was used as immunogen. The epitope has been mapped to the inter-SH2 spacer region of p85α. The antibody will block lipids binding to this region.