Phosphatidylinositol (3,4)-bisphosphate (PtdIns(3,4)P₂) is a minor phospholipid component of cell membranes, it is however an important second messenger. The generation of PtdIns(3,4)P₂ at the plasma membrane activates a number of important cell signalling pathways.

PtdIns(3,4)P₂ is dephophosphorylated by the phosphatase, PTEN on the 3 position of the inositol ring and by the TPTE (transmembrane phosphatases with tensin homology) family of phosphatases on the 4 position of the inositol ring.

The PH domain in a number of proteins binds to PtdIns(3,4)P₂ including the PH domain in PKB. The generation of PtdIns(3,4)P₂ at the plasma membrane upon the activation of class I PI 3-kinases and SHIP phosphatases causes these proteins translocate to the plasma membrane and accordingly effects their activity.

See also

Phosphatidylinositol 3-phosphate

Phosphatidylinositol 4-phosphate

Phosphatidylinositol 5-phosphate

Phosphatidylinositol (3,5)-bisphosphate

Phosphatidylinositol (4,5)-bisphosphate

Phosphatidylinositol (3,4,5)-trisphosphate