ホスファチジルイノシトール二リン酸、ホスファチジルイノシトール2リン酸、ホスファチジルイノシトール-4,5-二リン酸
出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/09/10 00:16:26」(JST)
Names | |
---|---|
IUPAC name
1,2-Diacyl-sn-glycero-3-phospho-(1-D-myo-inositol 4,5-bisphosphate)
|
|
Identifiers | |
CAS Registry Number
|
245126-95-8 Y |
ChemSpider | 21169207 N |
InChI
|
|
Jmol-3D images | Image |
PubChem | 5497157 |
SMILES
|
|
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 verify (what is: Y/N?) | |
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.[1]
PtdIns(4,5)P2 is formed primarily by the type I phosphatidylinositol 4 phosphate 5 kinases from PI(4)P.
The fatty acids of PIP2 are variable in different species and tissues, but studies show the most common fatty acids are stearic in position 1 and arachidonic in 2.[2]
PtdIns(4,5)P2 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. PIP2 regulates the function of many membrane proteins and ion channels, such as the M-channel. The products of the PLC catalyzation of PIP2 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.
Class I PI 3-kinases phosphorylate PtdIns(4,5)P2 forming phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3). Both PtdIns(3,4,5)P3 and PtdIns(4,5)P2 not only act as substrates for enzymes but also serve as docking phospholipids that bind specific domains that promote the recruitment of proteins to the plasma membrane and subsequent activation of signaling cascades.
Inwardly rectifying potassium channels have been shown to require docking of PIP2 for channel activity.[4][5]
PIP2 is regulated by many different components. One emerging hypothesis is that PIP2 concentration is maintained locally. Some of the factors involved in PIP2 regulation are[6]
PIP2 cleavage to IP3 and DAG initiates intracellular calcium release and PKC activation.
|accessdate=
requires |url=
(help)
|
|
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
リンク元 | 「ホスファチジルイノシトール2リン酸」「ホスファチジルイノシトール二リン酸」「ホスファチジルイノシトール-4,5-二リン酸」「ホフファチジルイノシトール 4,5-ビスリン酸」「PtdIns-4,5-P2」 |
関連記事 | 「bisphosphate」「phosphatidylinositol」 |
.