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1、Lodish Berk Kaiser Krieger scott Bretscher Ploegh MatsudairaMOLECULAR CELL BIOLOGYSEVENTH EDITIONCHAPTER 10Biomembrane Structure Copyright 2013 by W. H. Freeman and CompanyChapter OpenerFigure 10.1 Fluid mosaic model of biomembranes.Integral membrane proteinLipid-anchored proteinPeripheral membrane

2、proteinFigure 10.2 Eukaryotic cell membranes are dynamic structures.As the virus core buds from the cell, it es enveloped by a membrane derived from the cells plasma membrane that contains specific viral proteinsFigure 10.3 The bilayer structure of biomembranes.Experimental Figure 10.4 Formation and

3、 study of pure phospholipid bilayers.Figure 10.5 The faces of cellular membranes.Cytosolic faceExoplasmic faceOnly fourorganelles having two membranes-nucleus-mitochondrion-chloroplast- autophagosomeFigure 10.6 Faces of cellular membranes are conserved during membrane budding and fusion.Figure 10.7

4、Variation in biomembranes in different cell types.Smooth and flexible Tufts of cilia projecting from the ependymal cellsFigure 10.8 Three classes of membrane lipids.Figure 10.9 Gel and fluid forms of the phospholipid bilayer.Gel- to-fluid transitionExperimental Figure 10.10 Fluorescence recovery aft

5、er photobleaching (FRAP) experiments can quantify the lateral movement of proteins and lipids within the plasma membrane.Most lipid and many proteins are laterally mobile in biomembranesFigure 10.11 Effect of lipid composition on bilayer thickness and curvature.Figure 10.12 Specificity of phospholip

6、ases.Each type of phospholipase cleaves one of the susceptible bonds shown in red.Phospholipase, enzymes that cleave various bonds in the hydrophilic ends of phospholipids.These enzymes have an important role in the degradation of damaged or aged cell membranesFigure 10.13 Lipid droplets form by bud

7、ding and scission from the ER membrane.Figure 10.14 Structure of glycophorin A, a typical single-pass transmembrane protein.Hydrophobic (uncharged) side chains (red spheres)Heavily glycosylated, with the carbohydrate side chains (green diamonds)Figure 10.15 Structural models of two multipass membran

8、e proteins.Figure 10.16 Annular phospholipids.Figure 10.17 Charged residues can orchestrate assembly of multimeric membrane proteins.Figure 10.18 Structural model of one subunit of OmpX, a porin found in the outer membrane of E. coli.Figure 10.19 Anchoring of plasma-membrane proteins to the bilayer

9、by covalently linked hydrocarbon groups.GPI: glycosylphosphatidylinositol糖基化磷脂酰肌醇Figure 10.20 Human ABO blood group antigens.All humans have the enzymes for synthesizing O antigen.These transmembrane glycoprotein are always oriented-all carbohydrate chain are in exoplasmic domain (fig. 10-15) Person

10、s with typeA blood also have a glycosyltransferase that adds an extra N-acetylgalactosamine to O antigen to form A antigen.Figure 10.21 Lipid-binding surface and mechanism of action of phospholipase A2.When docked on a model lipid membrane, positively charged residues of the interfacial binding site

11、 bind to negatively charged polar groups at the membrane surface. This binding triggers a small conformational change, opening a channel lined with hydrophobic amino acids that leads from the bilayer to the catalytic site. As a phospholipid moves into the channel, an enzyme-bound Ca2+ ion (green) bi

12、nds to the head group, positioning the ester bond to be cleaved next to the catalytic site.This interfacial binding surface contains a rim of positively charged arginine and lysine residues shown in blue surrounding the cavity of the catalytic active siteFigure 10.22 Structures of four common deterg

13、ents.Figure 10.23 Solubilization of integral membrane proteins by nonionic detergents.Critical micelle concentration (CMC), at which micelles form is characteristic of each detergent and is a function of the structure of its hydrophobic and hydrophilic partsUN Figure 10.1Figure 10.24 Binding of a fa

14、tty acid to the hydrophobic pocket of a fatty-acid-binding protein (FABP).Figure 10.25 Phospholipid synthesis in ER membrane.Figure 10.26 Cholesterol biosynthetic pathway.1. Rate-controlling step2. HMG-CoA reductaseWhose transmembrane segments are embedded in theER membrane and Containing sterol-sen

15、sing domainIn the cytosol and ER membraneAtherosclerosisAtherosclerosis: cholesterol-dependent clogging of the arteries-Characterized by the progressive deposition of cholesterol and other lipids, cells, and extracellular matrix material in the inner layer of the way of an artery.Statins: most successful anti-atherosclerosis medicine -binds to HMG-CoA reductase, thus lowering the cholesterol biosysnthe