In 1987 I attended a meeting at Cold Spring Harbor on phosphatidylinositol signaling that turned out to be pivotal for me. A few years earlier I'd helped show that a phosphatidylinositol (PI) kinase activity copurified with various oncoprotein tyrosine kinases, and that this association was critical for the ability of these oncoproteins to transform cells in culture. We had begun to purify and characterize the PI kinase activity and had made a surprising observation.
A bit of background: PI kinases are enzymes that add phosphate residues to one of the five available hydroxyl groups of the inositol moiety of the membrane lipid, phosphatidylinositol. In the mid-1980s, only two phosphorylated forms of phosphatidylinositol were known to exist: phosphatidylinositol-4-phosphate (PI-4-P) and phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2). Shortly before the meeting in Cold Spring Harbor, while going over some thin-layer chromatograms of the lipid products of PI kinase assays performed by my graduate ...
