High impact information on Phosphatidylinositol 4,5-diphosphate

• We consider here the roles of the major phosphatidylinositol-4,5-diphosphate (PIP2) binding protein, MARCKS, and PIP2 levels in controlling cytoskeleton dynamics [1].
• Localization of the ATP/phosphatidylinositol 4,5 diphosphate-binding site to a 39-amino acid region of the carboxyl terminus of the ATP-regulated K+ channel Kir1.1 [2].
• However, the GRP1 PH domain was unique among these proteins in its striking selectivity for PtdIns(3,4, 5)P(3) versus phosphatidylinositol 4,5-diphosphate (PtdIns(4,5)P(2)), for which it exhibits about 650-fold lower apparent affinity [3].
• The activity and the rate of activation of CALPA, but not CALPB, could be activated by phosphatidylinositol 4,5-diphosphate, phosphatidylinositol 4-monophosphate, phosphatidylinositol, and phosphatidic acid [4].
• SP-D bound to neither phosphatidylinositol 4-monophosphate nor phosphatidylinositol 4,5-diphosphate [5].

Biological context of Phosphatidylinositol 4,5-diphosphate

• Stimulation of platelets and other secretory cells by agonists results in the degradation of phosphoinositides by phospholipase C. Kinetic studies suggest that hydrolysis of phosphatidylinositol 4,5-diphosphate (PI-4,5-P2) is an initial event in this process [6].
• Inhibition by ACTH 1-24 of the endogenous phosphorylation of B-50 protein in membranes was associated only with an enhancement of the phosphorylation of phosphatidyl-inositol 4-phosphate to phosphatidylinositol 4,5-diphosphate [7].
• An outstanding issue is whether phosphatidylinositol 4,5-diphosphate and related species act as true second messengers in signaling or behave in a manner analogous to an enzymatic cofactor [8].

Anatomical context of Phosphatidylinositol 4,5-diphosphate

• Phosphatidylinositol (PtdIns), phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-diphosphate [PtdIns(4,5)P2] were isolated from the pancreas of rats fed an ethanol-containing liquid diet for 24 days and from the corresponding pair-fed controls [9].
• Localization of phosphatidylinositol 4,5-diphosphate on the stereocilia of cochlear hair cells [10].
• The storage of Bufo arenarum oocytes decreased their ability to become fertilized "in vitro". The stimulation with carbachol of "young oocytes" showed a persistent hydrolysis with phosphatidylinositol 4,5 diphosphate (PIP2) while in "aged oocytes" both phosphatidylinositol 4 phosphate (PIP) and PIP2 were hydrolyzed at a non-significant level [11].

Associations of Phosphatidylinositol 4,5-diphosphate with other chemical compounds

• Incubation of 32P-labelled erythrocyte membranes with Mg2+ causes little breakdown of phosphatidylinositol 4,5-bisphosphate, the parent compound from which both glycerophosphoinositol 4,5-bisphosphate and inositol 1,4,5-trisphosphate are derived [12].

References