Phosphatidylinositol-bisphosphate (PtdIns(3,5)P₂ or PI(3,5)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 important in distinguishing cell compartments. The generation of PtdIns(3,5)P₂ in intracellular membranes by the lipid kinase PIKfyve recruits a number of important proteins involved in regulating intracellular trafficking.

PtdIns(3,5)P₂ is dephophosphorylated at the 5 position by the phosphatase FIG4

Fig4

Polyphosphoinositide phosphatase also known as phosphatidylinositol 3,5-bisphosphate 5-phosphatase or SAC domain-containing protein 3 is an enzyme that in humans is encoded by the FIG4 gene.- Function :...

, and by members of the myotubularin

Myotubularin

Myotubularin domain represents a region within eukaryotic myotubularin-related proteins that is sometimes found with . Myotubularin is a dual-specific lipid phosphatase that dephosphorylates phosphatidylinositol 3-phosphate and phosphatidylinositol -bi-phosphate...

 lipid 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...

 family at the 3 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 generating Phosphatidylinositol 5-phosphate

Phosphatidylinositol 5-phosphate

Phosphatidylinositol 5-phosphate is one of the seven phosphoinositides, and is the last to have been discovered to be naturally occurring....

 (PtdIns5P).

The phosphoinositide-binding domain in a number of proteins binds to PtdIns(3,5)P₂, including the PH domain in centaurin-β2 , the PX domain

PX domain

The PX domain is a phosphoinositide-binding structural domain involved in targeting of proteins to cell membranes.This domain was first found in P40phox and p47phox domains of NADPH oxidase...

 of SNX1

SNX1

Sorting nexin-1 is a protein that in humans is encoded by the SNX1 gene. The protein encoded by this gene is a sorting nexin. SNX1 is a component of the retromer complex.- Function :...

 , and a WD40 repeat

WD40 repeat

The WD40 repeat is a short structural motif of approximately 40 amino acids , often terminating in a tryptophan-aspartic acid dipeptide...

domain in Atg18p.