Figure 1.

Interconversion of the phosphoinositides PI(3,4,5)P3 and PI(4,5)P2 by phosphorylation/dephosphorylation at the 3 position of the inositol ring (bold arrow). In cells of D. discoideum both the PI3-kinases and the PI3-phosphatase PTEN shuttle between a cytoplasmic and an activated membrane-bound state. R1 and R2, hydrophobic membrane anchors of the phosphoinositides.