Phosphatidylinositol (3,4,5)-trisphosphate

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Chemical structure of sn-1-stearoyl-2-arachidonoyl phosphatidylinositol 3,4,5-trisphosphate

Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) commonly abbreviated to PIP3 is the product of the class I phosphoinositide 3-kinases (PI 3-kinases) activity on phosphatidylinositol (4,5)-bisphosphate.

PtdIns(3,4,5)P3 is dephophosphorylated by the phosphatase, PTEN on the 3 position and by SHIPs (SH2-containing inositol phosphatase) on the 5' position of the inositol ring.

The PH domain in a number of proteins binds to PtdIns(3,4,5)P3. Such proteins include Akt/PKB, PDK1, Btk1 and ARNO. The generation of PtdIns(3,4,5)P3 at the plasma membrane upon the activation of class I PI 3-kinases causes these proteins to translocate to the plasma membrane and accordingly effects their activity.