Courtesy of Cantley lab
In the mid 1980s we discovered a phosphatidylinositol kinase that co-purified with several oncoproteins and that correlated with cell transformation. When my graduate student Malcolm Whitman presented his results at a lab meeting, I noticed that in this autorad, the phosphatidylinositol phosphate produced by the oncoprotein-associated PI kinase (Type I) migrated slightly more slowly in thin layer chromatography (TLC) than that produced by PI 4-kinase (Type II).
The reproducibility of this slight difference convinced me that the two enzymes were making chemically different phosphoinositides, and raised the exciting possibility that Type I PI kinase was in a new signaling pathway distinct from the canonical PI turnover pathway that uses PI 4-kinase.1
With help from Len Stephens and C. Peter Downes, we ultimately showed that the Type I PI kinase phosphorylated the 3 position of the inositol ring, opening up a new field of research with enormous implications for the understanding of cancer.
- Lewis C. Cantley, Harvard Medical School