Laboratory of Plasma Membrane Receptors, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
Cell Mol Life Sci. 2010 Dec;67(23):3927-46. doi: 10.1007/s00018-010-0432-5. Epub 2010 Jun 18.
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] is a minor lipid of the inner leaflet of the plasma membrane that controls the activity of numerous proteins and serves as a source of second messengers. This multifunctionality of PI(4,5)P(2) relies on mechanisms ensuring transient appearance of PI(4,5)P(2) clusters in the plasma membrane. One such mechanism involves phosphorylation of PI(4)P to PI(4,5)P(2) by the type I phosphatidylinositol-4-phosphate 5-kinases (PIP5KI) at discrete membrane locations coupled with PI(4)P delivery/synthesis at the plasma membrane. Simultaneously, both PI(4)P and PI(4,5)P(2) participate in anchoring PIP5KI at the plasma membrane via electrostatic bonds. PIP5KI isoforms are also selectively recruited and activated at the plasma membrane by Rac1, talin, or AP-2 to generate PI(4,5)P(2) in ruffles and lamellipodia, focal contacts, and clathrin-coated pits. In addition, PI(4,5)P(2) can accumulate at sphingolipid/cholesterol-based rafts following activation of distinct membrane receptors or be sequestered in a reversible manner due to electrostatic constrains posed by proteins like MARCKS.
磷脂酰肌醇 4,5-二磷酸[PI(4,5)P(2)]是质膜内层的一种少量脂质,它控制着许多蛋白质的活性,并作为第二信使的来源。PI(4,5)P(2)的这种多功能性依赖于确保其在质膜中短暂出现的机制。其中一种机制涉及在离散的膜位置通过 I 型磷脂酰肌醇-4-磷酸 5-激酶(PIP5KI)将 PI(4)P磷酸化为 PI(4,5)P(2),同时在质膜上进行 PI(4)P 的输送/合成。同时,PI(4)P 和 PI(4,5)P(2)都通过静电键参与将 PIP5KI 锚定在质膜上。PIP5KI 同工型也通过 Rac1、talin 或 AP-2 选择性募集和激活质膜,以在皱襞和片状伪足、焦点接触和网格蛋白包被的陷窝中生成 PI(4,5)P(2)。此外,PI(4,5)P(2)可以在特定膜受体激活后在鞘脂/胆固醇基筏上聚集,或者由于 MARCKS 等蛋白引起的静电约束以可逆的方式被隔离。