Phosphatidylinositol-bisphosphate (PtdIns(3,4)P₂) is a minor phospholipid

Phospholipid

Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...

 component of cell membranes, yet an important second messenger. The generation of PtdIns(3,4)P₂ at the plasma membrane activates a number of important cell signaling pathways.

PtdIns(3,4)P₂ is dephophosphorylated by the phosphatase

Phosphatase

A phosphatase is an enzyme that removes a phosphate group from its substrate by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group . This action is directly opposite to that of phosphorylases and kinases, which attach phosphate groups to their...

 INPP4B on the 4 position of the inositol

Inositol

Inositol or cyclohexane-1,2,3,4,5,6-hexol is a chemical compound with formula 6126 or 6, a sixfold alcohol of cyclohexane. It exists in nine possible stereoisomers, of which the most prominent form, widely occurring in nature, is cis-1,2,3,5-trans-4,6-cyclohexanehexol, or myo-inositol...

 ring and by the TPTE

TPTE

Putative tyrosine-protein phosphatase TPTE is an enzyme that in humans is encoded by the TPTE gene.-Further reading:...

 (transmembrane phosphatases with tensin homology) family of phosphatases on the 3 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

PKB

PKB is a three-letter abbreviation that may refer to:* Państwowy Korpus Bezpieczeństwa, a Polish underground police force during World War II* The National Awakening Party of Indonesia, from the abbreviation for its name in Indonesian...

. The generation of PtdIns(3,4)P₂ at the plasma membrane upon the activation of class I PI 3-kinases and SHIP

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

phosphatases causes these proteins to translocate to the plasma membrane, thereby effecting their activity.