Program in Cell Biology, Hospital for Sick Children, 686 Bay Street, Toronto, ON, Canada M5G 0A4.
Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
Mol Biol Cell. 2021 Feb 1;32(3):301-310. doi: 10.1091/mbc.E19-08-0436. Epub 2020 Dec 2.
Anionic phospholipids can confer a net negative charge on biological membranes. This surface charge generates an electric field that serves to recruit extrinsic cationic proteins, can alter the disposition of transmembrane proteins and causes the local accumulation of soluble counterions, altering the local pH and the concentration of physiologically important ions such as calcium. Because the phospholipid compositions of the different organellar membranes vary, their surface charges are similarly expected to diverge. Yet, despite the important functional implications, remarkably little is known about the electrostatic properties of the individual organellar membranes. We therefore designed and implemented approaches to estimate the surface charges of the cytosolic membranes of various organelles in situ in intact cells. Our data indicate that the inner leaflet of the plasma membrane is most negative, with a surface potential of approximately -35 mV, followed by the Golgi complex > lysosomes > mitochondria ≈ peroxisomes > endoplasmic reticulum, in decreasing order.
阴离子磷脂可以使生物膜带有净负电荷。这种表面电荷产生电场，有助于募集外在的阳离子蛋白，改变跨膜蛋白的分布，并导致可溶性抗衡离子在局部聚集，改变局部 pH 值和生理上重要的离子（如钙）的浓度。由于不同细胞器膜的磷脂组成不同，它们的表面电荷也预计会有所不同。然而，尽管具有重要的功能意义，但对于单个细胞器膜的静电特性却知之甚少。因此，我们设计并实施了几种方法来估计完整细胞中各种细胞器胞质膜的表面电荷。我们的数据表明，质膜的内叶最负，表面电势约为-35 mV，其次是高尔基体复合物>溶酶体>线粒体≈过氧化物酶体>内质网，依次递减。
