| Lipid Extraction from HeLa Cells, Quantification of Lipids, Formation of Large Unilamellar Vesicles (LUVs) by Extrusion and in vitro Protein-lipid Binding Assays, Analysis of the Incubation Product by Transmission Electron Microscopy (TEM) and by Flotation across a Discontinuous Sucrose Gradient
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Author:
Date:
2016-10-20
[Abstract] Dissecting the interactions established between proteins and membranes in a given type of cells is not an easy task. Using a cell-free system of large unilamellar vesicles (LUVs) to analyze these interactions may help decipher these interactions and identify potential membrane deformations induced by the proteins incubated with these LUVs. This article describes the protocols for 1) extraction of total lipids from eukaryotic cells using the method developed by Bligh and Dyer (1959), 2) the quantification of glycerophospholipids by gas chromatography after methanolysis, followed by 3) the formation of LUVs by extrusion, 4) protein-lipid binding assay, 5) analysis of the incubation product by transmission electron microscopy (TEM) and by flotation across a discontinuous sucrose gradient and ...
[摘要] 解剖在给定类型的细胞中蛋白质和膜之间建立的相互作用不是一个容易的任务。使用大单层囊泡（LUV）的无细胞系统来分析这些相互作用可以帮助破译这些相互作用和识别由与这些LUV孵育的蛋白质诱导的潜在的膜变形。本文介绍了1）使用由Bligh和Dyer（1959）开发的方法从真核细胞中提取总脂质，2）在甲醇分解后通过气相色谱法定量甘油磷脂，然后3）通过挤出形成LUV的方案， 4）蛋白质 - 脂质结合测定，5）通过透射电子显微镜（TEM）和通过不连续蔗糖梯度浮选分析孵育产物，最后，6）通过免疫印迹分析蛋白质并通过碘素熏蒸显示甘油磷脂。
[背景] 包含巨单层囊泡（GUV;由单个磷脂双层组成，直径大于1μm）或脂质体孵育的无细胞系统与重组蛋白可能有助于了解这些相互作用。根据它们的直径和层数，脂质体被分为小的单层囊泡（SUV;由单个磷脂双层构成的囊泡，直径在20和100nm之间），大的单层囊泡（LUV;由单个双层磷脂，并且直径在100和400nm之间），大多层囊泡（MLV;由多个磷脂双层构成且直径在200nm和3μm之间的囊泡）和多泡囊泡（MVV）;由囊泡组成的大囊泡单个双层磷脂，并含有几个较小的囊泡，每个囊泡由单个双层磷脂组成）。 ...
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| Determination of VPS34/PIK3C3 Activity in vitro Utilising 32P-γATP
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Author:
Date:
2016-08-20
[Abstract] VPS34 is the only class III phosphatidylinositol-3-kinase (PI3K) in mammalian cells and produces the vast majority of cellular phosphatidylinositol-3-phosphate [PI(3)P]. PI(3)P is a key signalling lipid that plays many membrane trafficking roles in processes such as endocytosis and autophagy. VPS34 is a key cellular regulator, loss of function can have catastrophic effects and is embryonic lethal (Zhou et al., 2011). The levels of cellular PI(3)P can be determined by fluorescent staining techniques and can be used to monitor effects upon VPS34 activity, however it is important to verify that any changes are mediated by VPS34, particularly as alternate pathways of PI(3)P production are possible such as via class II PI3Ks (Devereaux et al., 2013). Assaying VPS34 activity ...
[摘要] VPS34是哺乳动物细胞中唯一的III类磷脂酰肌醇-3-激酶（PI3K），并且产生绝大多数细胞磷脂酰肌醇-3-磷酸[PI（3）P]。 PI（3）P是一个关键的信号脂质，在诸如内吞作用和自噬的过程中起许多膜运输的作用。 VPS34是关键的细胞调节剂，功能丧失可具有灾难性作用并且是胚胎致死的（Zhou等人，2011）。 细胞PI（3）P的水平可以通过荧光染色技术确定，并且可以用于监测对VPS34活性的影响，然而重要的是验证任何变化由VPS34介导，特别是作为PI（3）的替代途径， P生产是可能的，例如通过II类PI3K（Devereaux等人，2013）。 直接在体外测定VPS34活性可以是描绘特定刺激的作用的关键阶段。
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