5.3 An overview of the structure of the plasma membrane Investigation of cell membrane in early years 1925 E Gorter E grendel Leaf lamellar model 1935 H Davson Danielli Sandwith model 1959 J D. Robertson The concept of the unit membrane 1972S.J. Singer G Nicolson Fluid-mosaic model In fluid-mosaic model, the proteins occur as a <mosaic of discontinuous particles that penetrate deeply into, and even completely through, the lipid sheet. Most importantly, the fluid-mosaic model presents cellular membranes as dynamic structure in which the components are mobile and capable of coming together to engage in various types of transient or semipermanent interactions
. 5.3 An overview of the structure of the plasma membrane Investigation of cell membrane in early years 1925 E.Gorter & E. Grendel Leaf lamellar model 1935 H.Davson & J. Danielli Sandwith model 1959 J.D. Robertson The concept of the unit membrane 1972 S.J. Singer & G. Nicolson Fluid-mosaic model In fluid-mosaic model, the proteins occur as a <mosaic > of discontinuous particles that penetrate deeply into, and even completely through, the lipid sheet. Most importantly, the fluid-mosaic model presents cellular membranes as dynamic structure in which the components are mobile and capable of coming together to engage in various types of transient or semipermanent interactions
HCHHCH HCI Stationary Movable HCHHCH barrier HCH HCH ICH HCH C 比 (c)
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53.1生物膜的“流体镶嵌模型” 1972年 SJ singer和 G Nicolson提出生物膜流体镶嵌模型,二十多 年来,通过大量实验研究,人们对生物膜结构的认识不断地丰富 和深化,但是这一生物膜动态结构的概念一直不失为膜生物学的 核心原理( Central dogma)。在流体镶嵌模型中,如同以往的模 式,脂双分子层仍被看作为膜的核心层,但是脂分子是以流体状 态或液态存在于膜中,能够在其中作旋转( rotation)或侧向运动 ( moving laterally)(图6.2)。在这一模型中,膜蛋白颗粒不连 续地镶嵌于脂双分子层中,深深地穿入或完全透过脂片层。这个 模型描绘这样一个图象,即不同功能的蛋白质漂浮( floating)于 二维的流体中(two- dimensional liquid),所以被称之为流体镰 嵌模型。在流体镶嵌模型中,最重要的是细胞膜是以动态结构 ( dynamic structure)存在,膜的结构成分在其中可以移动并能 够聚集组装在一起,进行各种类型的暂时或永久的相互作用。后 来,人们在此基础上,又提出一些进一步的假设式模型。但是, 实际上人们已经很难再以某些简单的模式去描绘如此丰富多彩的 生物膜。人们越来越关注与多种多样的细胞功能和状态相适应的 膜结构的多样性、多形性和不对称性及其动态特性
5.3.1 生物膜的“流体镶嵌模型” 1972年S.J singer 和 G.Nicolson提出生物膜流体镶嵌模型，二十多 年来，通过大量实验研究，人们对生物膜结构的认识不断地丰富 和深化，但是这一生物膜动态结构的概念一直不失为膜生物学的 核心原理（Central dogma）。在流体镶嵌模型中，如同以往的模 式，脂双分子层仍被看作为膜的核心层，但是脂分子是以流体状 态或液态存在于膜中，能够在其中作旋转（rotation）或侧向运动 （moving laterally）（图6.2）。在这一模型中，膜蛋白颗粒不连 续地镶嵌于脂双分子层中，深深地穿入或完全透过脂片层。这个 模型描绘这样一个图象，即不同功能的蛋白质漂浮（floating）于 二维的流体中（two-dimensional 1iquid），所以被称之为流体镶 嵌模型。在流体镶嵌模型中，最重要的是细胞膜是以动态结构 （dynamic structure）存在，膜的结构成分在其中可以移动并能 够聚集组装在一起，进行各种类型的暂时或永久的相互作用。后 来，人们在此基础上，又提出一些进一步的假设式模型。但是， 实际上人们已经很难再以某些简单的模式去描绘如此丰富多彩的 生物膜。人们越来越关注与多种多样的细胞功能和状态相适应的 膜结构的多样性、多形性和不对称性及其动态特性
Protein molecule Polar pore helix Pho Figure 44 A brief history of the structure of the plasma face of most membrane proteins, as well as a small percent. membrane (a)A revised 1954 version of the Dayson. Danielli model showing the lipid bilayer, which is lined on age of the phospholipids, contain short chains of sugars. making them glycoproteins and glycolipids. Those portions both surfaces by a monomolecular layer of proteins that ex of the polypeptide chains that extend through the lipid bi- tend through the membrane to form protein-lined pores, br Layer typically occur as a helices composed of hydrophobic The fluid-mosalc model of membrane structure as initially amino acids. fa: From J F. Dhuiclli Colston Papers 7:8,195 Proposed by Singer and Nicolson in 1972. Unlike previous Ir reprinted mth permission from S. I. Singer an G. L, models, the proteins penetrate into and through the lipid bi. Science 175:720, 1972: copyright 1972 American Association for Layer. (e) A current representation of the plasma membrane the Adewncementt of Science. s: From D. Voet and I. G, Veet. Bio- showing the same basic organization as that proposed by chemistry, and el, copyright D 1995. Jom wwev SovsInc Singer and Nicolson. We now know that the extenal sur. Reyrtmief bu permission ef Jon Win 6 Sans, inc)