细胞生物学课件-chapter3-membrane structure

ChapterChapter3MembraneTheLipidMembraneFigure.EssentialCellBiology(©GarlandScienceAbriefhistoryofplasmamembraneE.Oveiton,LipidNatureofE.GorterandF.Grendel,LipidH.Daveson,SandwichJ.Daniclli,PMalsocontainJ.D.Robertson,TEM,UnitS.J.SingerandG.L.Nicolson,FluidmosaicFigure.AcellmembranecanbeviewedinanumberofAAcellmembranehumanbloodcellincrosstwo- Fluidmosaic(twokeyFigure.EssentialCellBiology(©GarlandScienceLipidRaft(Simon,Raftsareenrichedwithcholesterolandgalactosylceramide(GalCer半乳糖神经酰胺or半乳糖脑苷脂galactocerebrosideandstuddedwithproteins.Nature387:569-LipidRaftsmodel;FunctionalraftsincellmembranesFigure Lipid alkalinephosphatase碱性磷酸L-α-二油酸磷脂酰

Lipid3.13.1TheLipidThemainfunctionofcellTheplasmamembraneactasselective质质内biomembrane=plasmamembrane+internalFigure.EssentialCellBiology(©GarlandScienceTheplasmamembraneisinvolvedincellcommunication,importandexportofmolecules,andcellgrowthandmotilityCellandFigure.EssentialCellBiology(©GarlandScienceLocalizationandorganizationoforFigure.EssentialCellBiology(©GarlandScienceThebasiccompositionsofsomebio-MembranelipidformbilayersinPhosphatidylcholine(磷脂酰胆碱isthemostphospholipidcell Figure.EssentialCellBiology(©GarlandScienceFigure.MolecularBiologyoftheCell(©GarlandScienceFourmajorphospholipidsinmammalianplasma Figure.MolecularBiologyoftheCell(©GarlandScience

鞘氨醇 Differenttypesofmembranelipidsareallamphipathic(两亲的Figure.EssentialCellBiology(©GarlandScienceAhydrophilic亲水的moleculeacetoneattractswatermoleculesrequiresAhydrophobic疏水的molecule2-methylpropane(2-甲基丙烷tendstoavoidwatermolecules.Figure.EssentialCellBiology(©GarlandScienceFatmoleculesarehydrophobicwhereasphospholipidsareamphipathic两亲的Theenergycostisminimized,however,ifthehydrophobicmoleculesclustertogether,limitingtheircontactwithwatertothesmallestpossiblenumberofwatermolecules. Figure.EssentialCellBiology(©GarlandScienceAmphipathicphospholipidsformabilayerinFigure.EssentialCellBiology(©GarlandSciencePackingarrangementsofmoleculesinan微微双分Lipidmoleculesspontaneouslyformoneorotherstructureinwater,dependingontheirFigure.MolecularBiologyoftheCell(©GarlandSciencespontaneouslycloseinonthemselvestoformsealedFigure.EssentialCellBiology(©GarlandScienceCrawlingAmicroscopicviewofspermduringinvitrofertilizationPhospholipidinsolventTheareaddedPhospholipidinsolventTheareaddedtoaddedtosolventflatlipidFigure.EssentialCellBiology(©GarlandScienceLiposomeforLiposomeforDrugFigure.Liposome(1999)byKosiThemobilityofphospholipidmoleculesinanartificiallipidbilayerMembraneMembranefluidisduetolipidfluidFigure.MolecularBiologyoftheCell(©GarlandScienceThefluidityofthebilayerisstrictlyconfinedoneneedneedFigure.MolecularBiologyoftheCell(©GarlandScienceThefluidityofalipidbilayerdependsonitsJusthowfluidalipidbilayerisatagiventemperaturedependsonitsphospholipidcompositionand,inparticular,onthenatureofthehydrocarbontails:thecloserandmoreregular themoreviscous粘性andlessfluidtwomajorpropertiesoftails: numberofdoubleunsaturatedhydrocarbon-----morefluidsaturatedhydrocarbon----moresolidThestructureofCholesterolinaInanimalcells,membranefluidityismodulatedbytheinclusionofthesterolcholesterol.Cholesteroltendstostiffencellmembranes.Figure.MolecularBiologyoftheCell(©GarlandScienceCholesteroltendstostiffencellFigure.EssentialCellBiology(©GarlandScienceFigure.MolecularBiologyoftheCell(©GarlandScienceEvidencesofmembranecellFigure.MolecularBiologyoftheCell(©GarlandScienceFluorescenceRecoveryAfterPhotobleachingFRAPdenotesanopticaltechniquecapablefyingthetwodimensionallateraldiffusionofamolecularlythinfilmcontainingfluorescentlylabeledprobes,ortoexaminesinglecells.Thistechniqueisveryusefulinbiologicalstudiesofcellmembranediffusionandproteinbinding.Inaddition,surfacedepositionofafluorescingphospholipidbilayer(ormonolayer)allowsthecharacterizationofhydrophobicsurfacesintermsofsurfacestructureandfreeenergy.Figure.EssentialCellBiology(©GarlandScience

Disadvantages:itisimpossibletowhatindividualmoleculesare FluorescencelossinphotobleachingFLIP,isatechniqueinfluorescencemicroscopywhichcanbeusedtoexaminethemovementordiffusionofmoleculesinsidecellsormembranes.Typicallyacellmembraneislabelledwithafluorescentdye,andaspecificareaofthelabeledmembraneisbleachedusingthebeamfromaconfocallaserscanningmicroscope.Thefluorescenceintensityfromthatregionofthemembraneismeasuredovertime.Motionoffluorescentmoleculesintoandalongthemembraneslowlyrestoresthefluorescenceinthebleachedregion,whiledepletingthefluorescenceinotherregions(byexchangeofbleachedforunbleachedFLIPFLIPFigure.MolecularBiologyoftheCell(©GarlandScienceProteinsshowdifferentpatternsofmotion

Freeto

Corralledwithinasmall byotherFigure.EssentialCellBiology(©GarlandScienceTherolesofthefluidityofalipidItenablesmembraneproteintodiffuserapidlyintheplaneofthebilayerandtointeractoneanother.e.g.cellsignaling.Itpermitsmembranelipidsandproteinstodiffusefromsitewheretheyareinsertedintothebilayeraftertheirsynthesistootherregionsofthecell.Itallowsmembranestofusewithoneanotherandmixtheirmolecules.Itensuresthatmembranemoleculesaredistributedevenlybetweendaughtercellswhenacelldivides.Thelipidbilayeristhelipidbilayercompositionisty:twosideare

Figure.EssentialCellBiology(©GarlandScienceGlycolipid糖脂半乳糖脑苷 Figure.MolecularBiologyoftheCell(©GarlandScience

Figure. ThelipidasymmetryisestablishedandmaintainedasthemembranegrowsIneucaryoticcells,newphospholipidsaremanufacturedbyenzymefacesthecytosol.Figure.EssentialCellBiology(©GarlandScienceMembraneassemblybeginsintheCertainphospholipidsareconfinedtosideofLightLightgreen:PSYellow:PERed:PCBrown:SM磷脂拼接 翻转Figure.EssentialCellBiology(©GarlandScience

NewlysynthesizedphospholipidsareaddedtothecytosolicsideoftheERmembraneandthenredistributedbyenzymesthattransferthemfromonehalfofthelipidbilayertotheother.Theresultingcurvatureofthemembranemayactuallyhelpdrivesubsequentvesiclebudding.MembranesretaintheirorientationduringtransferbetweencellcompartmentsProteinattachedsugarfacingthenoncytosolicsideFigure.EssentialCellBiology(©GarlandScienceLipidasymmetryis duringmembranecytosolicsurfacenoncytosolicsurfaceMembranesretaintheirorientationevenaftertransferbetweencellFigure.MolecularBiologyoftheCell(©GarlandScienceEvidencesofmembraneFreezefracture:atechniqueforindicatingcellmembraneFigure. TheasymmetryoflipidisfunctionallyLightLightgreen:PSYellow:PERed:PCBrown:SMCombinewithLysorArgofglycophorinFigure.MolecularBiologyoftheCell(©GarlandScience聚糖，在细胞质表面附着于收缩性蛋白(红细胞膜内蛋白和肌动蛋白Convertingextracellularsignalsinto磷酸肌醇3激Figure.MolecularBiologyoftheCell(©GarlandScience3.2MembraneInanimal,proteinsconstituteabout50%of3.2MembranePlasmamembraneproteinshaveavarietyofFigure.EssentialCellBiology(©GarlandScienceFigure.EssentialCellBiology(©GarlandScienceMembraneproteinsassociatewiththelipidbilayerinvariouswaysA,B,C—Suchproteinsareknownasintegralmembraneproteins膜内在蛋白Theremainingmembraneproteinsareknowsasperipheralmembraneproteins膜周边蛋白.Figure.EssentialCellBiology(©GarlandScienceApolypeptidechainusuallycrossesthebilayerasanα-helixFigure.EssentialCellBiology(©GarlandScienceThepolypeptidechainofsometransmembranecrossesalipidbilayerasaβsheetthatiscurvedintoacylinder,formingan-endedkeg-likestructurecalledaβbarrel.Themoststrikingexampleofaβbarrelstructureisfoundintheporinprotein孔蛋白,whichformlarge,waterfilledporesinmitochondrialandbacterialmembranes.Figure.EssentialCellBiology(©GarlandScienceAsegmentofachaincrossingthelipidbilayerasanα-helixFigure.MolecularBiologyoftheCell(©GarlandScienceMembraneproteinatta entbyafattyacidchainoraprenyl含异戊二烯基的group Figure.MolecularBiologyoftheCell(©GarlandScienceConvertingasingle-chainmultipassproteinintoatwo-chainmultipassproteinFigure.MolecularBiologyoftheCell(©GarlandScienceStepsinthefoldingofamultipasstransemembraneFigure.MolecularBiologyoftheCell(©GarlandScienceMembraneproteinscanbesolubilizedindetergentsandpurifiedTwocommonlyuseddetergentsIthasanoninoizedbutpolarstructureatitshydrophilicend.Figure.EssentialCellBiology(©GarlandScienceMembraneproteinscanbesolubilizedbyamildFigure.EssentialCellBiology(©GarlandScienceTheuseofmildnonionicdetergentsforsolubilizing,purifying,andreconsitutingfunctionalmembraneproteinThemembraneproteinsdiffusemorefreelyandrapidlyinartificiallipidbilayersthanincellFigure.EssentialCellBiology(©GarlandScienceThecompletestructureisknownforrelativelyfewmembraneproteinsBacteriorhodopsin细菌视紫红质(或细菌紫膜质,嗜盐性细菌盐生盐杆菌的紫膜中存在的色素蛋白)andaphotosyntheticreactioncenter—membraneproteinsthathaveimportantrolesinthecaptureanduseofenergyfromsunlight.Bacteriorhodopsinisasmallprotein(250AA)foundinlargeamountsintheplasmamembraneofanarchaean,calledHalobacteriumhalobium盐生盐杆菌.Bacteriorhodopsinisatypeoftransporterprotein,aclassoftransmembraneproteinsthatmovemoleculesandironandoutofcells.Figure.EssentialCellBiology(©GarlandScienceBacteriorhodopsin细菌视紫红质actsasaportongetsitsenergydirectlyfromEachBacteriorhodopsinmoleculecontainsasinglelightabsorbingnonprotein-calledretinal视黄醛--thatgivestheproteinandthebacteriumadeeppurpleFigure.EssentialCellBiology(©GarlandScienceThephotosyntheticreactionChlorophyllRhodopseudomonasFigure.EssentialCellBiology(©GarlandScienceTheplasmamembraneisreinforcedbythecellcortex细胞皮层RedbloodcellsaresmallandhaveadistinctiveflattenedshapeThemaincomponentoftheircortexistheproteinspectrin血影蛋白along,thin,flexiblerodabout100nminlength.Itwithactinformsameshworkthatprovidessupportfortheplasmamembraneandmaintainsthecell’sshape.Figure.EssentialCellBiology(©GarlandScienceAspectrinmeshworkformsthecellcortexinhumanredbloodWhatWhatcanyousayaboutthetarnsmembraneproteinmobilityinthemembrane?Figure.EssentialCellBiology(©GarlandScienceCellscanrestrictthemovementofmembraneFormationofmouse-humanhybridcellsshowsthatplasmamembraneproteinscanmovelaterallyinthelipidbilayerFigure.EssentialCellBiology(©GarlandSciencePlasmamembraneproteintolocalizedareaswithinthebilayer,therebycreatingfunctionallyspecializesregions,ormembrane s,onthecellororganellesurface.extracellarcelldiffusionbarriers(tightjunction)proteinonanotherFigure.EssentialCellBiology(©GarlandScienceAmembraneproteinisrestrictedtoaoftheplasmamembraneofanepithelialcellintheFigure.EssentialCellBiology(©GarlandScienceIsamembranewithmanyanchoredIsamembranewithmanyanchoredproteinsstillfluid?ThecellsurfaceiscoatedwithManymembraneproteininanimalcellsaregly