*** Welcome to piglix ***

Phosphatidylinositol 4,5-bisphosphate

Phosphatidylinositol 4,5-bisphosphate
Phosphatidylinositol-4,5-bisphosphate.svg
Names
IUPAC name
1,2-Diacyl-sn-glycero-3-phospho-(1-D-myo-inositol 4,5-bisphosphate)
Identifiers
3D model (Jmol)
ChemSpider
PubChem CID
Properties
C47H80O19P3
Molar mass 1042.05 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)P2, also known simply as PIP2, is a minor phospholipid component of cell membranes. PtdIns(4,5)P2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins.

PtdIns(4,5)P2 is formed primarily by the type I phosphatidylinositol 4-phosphate 5-kinases from PI(4)P. In metazoans, PtdIns(4,5)P2 can also be formed by type II phosphatidylinositol 5-phosphate 4-kinases from PI(5)P.

The fatty acids of PtdIns(4,5)P2 are variable in different species and tissues, but the most common fatty acids are stearic in position 1 and arachidonic in 2.

PtdIns(4,5)P2 regulates the organization, polymerization, and branching of filamentous actin (F-actin) via direct binding to F-actin regulatory proteins (citation).

PtdIns(4,5)P2 recruits cytosolic septin monomers/oligomers to membrane surfaces via direct binding to the polybasic motif present in septin monomers (citation). The specificity of septins for PtdIns(4,5)P2 has yet to be thoroughly investigated, and it is plausible that

PIP2 functions as an intermediate in the [IP3/DAG pathway], which is initiated by ligands binding to G protein-coupled receptors activating the Gq alpha subunit. PtdIns(4,5)P2 is a substrate for hydrolysis by phospholipase C (PLC), a membrane-bound enzyme activated through protein receptors such as α1 adrenergic receptors. PtdIns(4,5)P2 regulates the function of many membrane proteins and ion channels, such as the M-channel. The products of the PLC catalyzation of PtdIns(4,5)P2 are inositol 1,4,5-trisphosphate (InsP3; IP3) and diacylglycerol (DAG), both of which function as second messengers. In this cascade, DAG remains on the cell membrane and activates the signal cascade by activating protein kinase C (PKC). PKC in turn activates other cytosolic proteins by phosphorylating them. The effect of PKC could be reversed by phosphatases. IP3 enters the cytoplasm and activates IP3 receptors on the smooth endoplasmic reticulum (ER), which opens calcium channels on the smooth ER, allowing mobilization of calcium ions through specific Ca2+ channels into the cytosol. Calcium participates in the cascade by activating other proteins.


...
Wikipedia

...