PIP2

Phosphatidylinositol 4,5-bisphosphate

Names
IUPAC name 1,2-Diacyl-sn-glycero-3-phospho-(1-D-myo-inositol 4,5-bisphosphate)
Identifiers
CAS Number	245126-95-8 Y
3D model (Jmol)	Interactive image
ChemSpider	21169207 N
PubChem CID	5497157
InChI InChI=1S/C47H85O19P3/c1-3-5-7-9-11-13-15-17-19-20-22-24-26-28-30-32-34-36-41(49)63-39(37-61-40(48)35-33-31-29-27-25-23-21-18-16-14-12-10-8-6-4-2)38-62-69(59,60)66-45-42(50)43(51)46(64-67(53,54)55)47(44(45)52)65-68(56,57)58/h11,13,17,19,22,24,28,30,39,42-47,50-52H,3-10,12,14-16,18,20-21,23,25-27,29,31-38H2,1-2H3,(H,59,60)(H2,53,54,55)(H2,56,57,58)/p-5/b13-11-,19-17-,24-22-,30-28-/t39?,42-,43+,44+,45-,46-,47-/m1/s1 N Key: CNWINRVXAYPOMW-WJUYXORRSA-I N InChI=1/C47H85O19P3/c1-3-5-7-9-11-13-15-17-19-20-22-24-26-28-30-32-34-36-41(49)63-39(37-61-40(48)35-33-31-29-27-25-23-21-18-16-14-12-10-8-6-4-2)38-62-69(59,60)66-45-42(50)43(51)46(64-67(53,54)55)47(44(45)52)65-68(56,57)58/h11,13,17,19,22,24,28,30,39,42-47,50-52H,3-10,12,14-16,18,20-21,23,25-27,29,31-38H2,1-2H3,(H,59,60)(H2,53,54,55)(H2,56,57,58)/p-5/b13-11-,19-17-,24-22-,30-28-/t39?,42-,43+,44+,45-,46-,47-/m1/s1 Key: CNWINRVXAYPOMW-XHXVUCGABS
SMILES O=P([O-])([O-])O[C@@H]1[C@@H](O)[C@H](OP([O-])(=O)OCC(COC(=O)CCCCCCCCCCCCCCCCC)OC(=O)CCC/C=C\C/C=C\C/C=C\C/C=C\CCCCC)[C@H](O)[C@H](O)[C@H]1OP([O-])([O-])=O
Properties
Chemical formula	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 YN ?)
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 G_q 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.