Figure 1.

Biosynthesis of PIP2 and PIP3 at plasma membrane-cytoplasm interface. The equilibrium between synthesis of PIP2 and PIP3 at membrane-cytoplasm interface is maintained through addition of phosphate groups (orange) by kinases (green), and its removal by phosphatases (red) at position 3,4, or 5 of the cytoplasmic inositol head group of phosphoinositides (PI). INPP4: inositol polyphosphate 4-phosphatase; SACM1L: SAC1 like phosphatidylinositide phosphatase; INPP5: inositol polyphosphate 5-phosphatase; TPIP: transmembrane phosphatase with tensin homology (TPTE) and PTEN homologous inositol lipid phosphatase