Phosphatidylinositol 3,4-bisphosphate
Phosphatidylinositol -bisphosphate is a minor phospholipid component of cell membranes, yet an important second messenger. The generation of PtdInsP2 at the plasma membrane activates a number of important cell signaling pathways.
PtdInsP2 is dephophosphorylated by the phosphatase INPP4B on the 4 position of the inositol ring and by the TPTE family of phosphatases on the 3 position of the inositol ring.
The PH domain in a number of proteins binds to PtdInsP2 including the PH domain in PKB. The generation of PtdInsP2 at the plasma membrane upon the activation of class I PI 3-kinases and SHIP phosphatases causes these proteins to translocate to the plasma membrane, thereby affecting their activity.
