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1、俺怎么越 看越象 乒乒乓乓，不要扔 西红柿 -_-b 俺们的进山 全家福， hoho COOH NH2 4.细胞膜中的脂筏及 膜穴系统 很早以前，人们就发现许多真核生物的细胞中 都可以分离得到抗去垢剂的膜微畴结构，英文简称 为DRMs（detergent-resistant membrane domains） ，但直到近年来DRMs才引起人们的广泛关注。这是 因为DRMs在细胞内的分选和细胞表面信号传导过程 中都表现出其特有的重要性。 这些在4去垢剂不溶的膜区域被认为是由鞘脂 类和胆固醇的动态聚集而形成，它们组成了相对稳 定的具有一定功能的畴结构漂浮于二维流动的细胞 膜中，人们形象地称之为“脂
2、筏”（Lipid rafts） 。 Functional rafts in cell membranes Nature387(1997)571 A new aspect of cell membrane structure is presented, based on the dynamic clustering of sphingolipids and cholesterol to form rafts that move within the fluid bilayer. - Simons EM476. YFP: EX516; EM529 The Existence of rafts in
3、 cell membranes (Rafts in living cells) Fluorescence resonance energy transfer measurements using fluorescent folate to show interactions of folate receptors when they are in proximity in rafts in living cells. Photonic force microscopy measurements of the size of rafts in living cells. Figure 1. Sc
4、aled model of the experimental situation: a sphere (r 5 108 nm) bound via an adsorbed antibody to a GPI-anchored protein that is part of a raft domain. The lipid bilayer is symbolized by the double row of gray dots with black sections symbolizing raft domains. The extent of the thermal position fluc
5、tuations observed in the experiments (6 60 nm) is marked. It is much smaller than the smallest estimates of the spacing of immobile cytoskeleton-anchored obstacles to free diffusion of 300500 nm (Sako and Kusumi, 1995). The cytoskeletal elements drawn here are 250 nm apart. Individual raft size is m
6、easured by photonic force microscopy Lipid Rafts Reconstituted in Model Membranes (1) Planar supported lipid layers constitute one model system that has the important advantage that bilayers may be constructed from two monolayers of different composition; thus, the inherent asymmetry of biological m
7、embranes may be mimicked. (2) Giant unilamellar vesicles (GUVs) (GUV composed of DOPC /cholesterol/ sphingomyelin (1:1:1) with 1 mol % GM1 ) are a second model system that provides a free standing bilayer, without potential substrate effects. (a) Non-raft mixture (POPC/cholesterol 2:1); (b) Raft- mixture (POPC/cholesterol/sphingomyelin 2:1:1). Both contain 0.5 mol % FL-DPPE. 登顶成功，可惜神仙都被一脸幸 福地俺们吓跑了。 膜分子生物学 游击队