复旦细胞课件-英文00cfc0c2

Chapter

Cytoskeleton1.1.A.A.ConceptionofCytoskeleton(NarrowAcomplexnetworkofinterconnectedmicrofilaments,microtubulesandintermediatefilamentsthatextendsthroughoutthecytosol. IntermediateB.B.TechniquesforstudyingtheFluorescentmicroscopyandElectronmicroscopy:Immunofluorescence:fluorescently-labeledantibodyFluorescence:microinjectintolivingcellsmicroscopy:invitromotilityassaysElectron:TritonX-100,MetalreplicaQuickfreezing-deepetchingEM ysis(inDifferencecentrifugation;SDS-Drugsandmutations(aboutC.C.Theself-assemblyanddynamicstructureofcytoskeletalfilamentsEachtypeofcytoskeletalfilamentisconstructedfromsmallerproteinsubunits.ThecytoskeletonisanetworkofthreefilamentousThecytoskeletonisadynamicstrucrurewithmany2.2.Microfilament,A.A.MFsaremadeofactinandinvolvedincellUsingATP,G-actinpolymerizestoformMF(F-B.B.MFassemblyand(1)(1)WithinaMF,alltheactinmonomersareorientedinthesamedirection,soMFhasapolarityMyosinisMyosinismotorfor(2)(2)Invitro,(Polymerization)bothendsoftheMFgrow,buttheplusendfasterthantheminus.Becauseactinmonomerstendtoaddtoafilament’splusendandleavefromitsminusend----(3)DynamicequilibriumbetweentheG-actinandpolymeric(3)DynamicequilibriumbetweentheG-actinandpolymericforms,whichisregulatedbyATPhydrolysisandG-actinconcentration.2.2Mechanismofactinpolymerization:3phasesofG-actinpolymerization.Criticalconcentration(Cc).Insteadystate,G-actinmonomersonlyexchangewithsubunitsatthefilamentendsbutthereisnonetchangeinthetotalmassofDuringtheelongationstate,oneendofthefilament,the(+)end,elongatesfivetotentimesfasterthandoestheopposite(-)end.ThisisbecauseCcvalueismuchlowerforG-actinadditionatthe(+)endthanforadditionatthe(-)Figure6-17ThethreephasesofG-actinpolymerizationin(4)(4)Dynamicequilibriumisrequiredforthecellfunctions.SomeMFsaretemporaryandothers(5)ThenucleationofactinfilamentsatthePMisfrequentlyregulatedbyexternalsignals,allowingthecelltochangeitsshapeandstiffnessrapidlyinresponsetochangesinitsexternalenvironment.Thisnucleationiscatalyzedbyacomplexofproteinsthatincludestwoactin-relatedproteins,orARPs(Arp2andArp3).ActinarraysinaC.C.SpecificdrugsaffectpolymerPreventtheadditionofnewmonomerstoexistingMFs,whicheventuallydepolymerize.Acyclicpeptidefromthedeathcapfungus,blocksthedepolymerizationofMFThoseThosedrugsdisruptthemonomer-polymerequilibrium,soarepoisonoustocellsD.D.Actin-bindingTheThestructuresandfunctionsofcytoskeletonaremainlycontrolledbyitsbindingAflin(promoteactingassembly),thymosinbeta4(inhibitsactinSomecytosolicproteinscontrolactin3differenttypesofstalbeactinfilamentParallelbundle:MFsisotacticparallelarrange，mainlyfoundinmicrovillusandfilopodium(Contractilebundle:MFsanti-parallelarrange,mainlyfoundinstressfibers(应力纤维)andcontractiveringofmitosis(有丝 收缩环)。Gel-likenetworkMFscross-linkedarrangemostbefoundincellcortexcytosol,细胞皮层(2)MF-binding成单体

白（nucleatingproteins）:actin-relatedproteins蛋白（monomer-sequesteringprotein）:封端（加帽）蛋白（End- )单体–聚合蛋白（monomer-polymerizingproteins）:抑制蛋（profilin）是一种与ATP-肌动蛋白单体结合的蛋白肌动蛋白纤维解聚蛋白（tinfilnt-dolzingpots）:cofilin、ADF以及蚕食蛋白与肌动蛋白纤维的减端结合，大大促进肌动蛋白纤维解聚成单体。交联蛋白（cross-linkingproteins）:ABP280和细丝蛋白,促进形成近纤维–切割蛋白（filament-severingproteins）:膜结合蛋白（membrane-bindingproteins）:连接膜与肌动蛋白的白质包括联结蛋白 的成员包括埃兹蛋（ezrin）、根蛋白（radixin）和膜突蛋白Modelofthecomplementaryrolesofprofilinandthymosinβ4inregulatingpolymerizationofG-actin.Actinfilamentsarelikewisestronglyaffectedbythebindingofaccessoryproteinsalongtheirsides.Actinfilamentsinmostcellsarestabilizedbythebindingoftropomyosin,anelongatedprotein.WhichcanpreventthefilamentfrominteractingwithotherAnotherimportantactinfilamentbindingprotein,cofilin,presentinalleucaryoticcells,whichdestabilizedactinfilaments(alsocalledactindepolymerizingfactor).Cofilinbindsalongthelengthoftheactinfilament,thefilamenttotwistalittlemoreInaddition,cofilinbindingcausealargeincreaseintherateofactinfilamenttreadmilling.TheThemodularstructuresoffouractin-cross-linkingTheTheformationoftwoofactinfilamentContractilebundlemediatedbyα-actininparallelbundlemediatedbyfimbrin.Gel-likeGel-likeActinfilamentsareoftennucleatedattheplasmamembrane.Thehighestdensityofactinfilamentsisatthecellperipheryformingcellcortex.Filamincross-linksactinfilamentsintoathree-dimensionalnetworkwiththephysicalpropertiesofagel.LossoffilamincausesabnormalcellE.Functionsof(1)(1)Maintaincell’sshapeandenforce(2)(2)Cellmigration(Fibroblastetetetactivationisacontrolledsequenceofactin ,,andcross-,(3)Microvillus:Supporttheprojectingmembraneof(3)Microvillus:Supporttheprojectingmembraneofintestinalepithelialcells(4)(4)StressComposedComposedofactinfilamentsandResponsetoResponseto

Stress

FocalcontactsResponseResponseto(5)(5)Contractilering:For(6)(6)MuscleOrganizationOrganizationofskeletalmuscle皮肤?蛋同伴皮肤?

平原皮肤球??蛋ProteinsProteinsplayimportantrolesinmuscleMyosin:Myosin:Theactinmotor MainlyMainlyinmuscleThickThickLight-chainLight-chainphosphorylationandtheregulationtheassemblyof intothickRopelikeRegulateMFtobindtotheheadof

Complex,Ca2+-ControlthepositionofTmonthesurfaceofMFThickandthinfilamentsslidingExcitation-Excitation-couplingActionCa2+riseinSchematicdiagramshowinghowaCa2+-releasechannelinthesarcoplasmicreticulummembraneisthoughttobeopenedbyavoltage-sensitiveSchematicdiagramshowinghowaCa2+-releasechannelinthesarcoplasmicreticulummembraneisthoughttobeopenedbyavoltage-sensitivetransmembraneproteinintheadjacentT-tubuleF.F.Smoothmusclecell(平滑肌细胞SmoothandSmoothandnonmusclecellcontractionareregulatedinamannerdistinctfromthatofskeletalmusclecellsCa2+ Ca2+- Bind ight

Myosin

with A.TubulinheterodimersA.TubulinheterodimersaretheproteinbuildingblocksofMTs3.Microtubule,ArrangementofArrangementofprotofilamentsinsinglet,double,andtripletMTs InInciliaandInIncentriolesandbasalB.B.MTsassemblefrommicrotubule-organizingcenters(MTOCs)Interphase:DynamicDynamicDividingMitoticDynamicDynamicCiliatedcell:BasalBasalBasalbodyC.C.CharacteristicsofMTinstabilityduetothestructuralbetweenagrowingandashrinkingmicrotubuleend.GTPaccidentallossofGTPcap;Rescue:ofGTPWhythecentrosomecanNoNocentriolesinPlantandMTMTarenucleatedbyaproteincomplexcontaining?-tubulinTheThecentrosomeisthemajorMTOCofanimalDrugsDrugsaffecttheassemblyofBindingtotubulindimers,preventMTsBindingtoMTs,stabilizeTheseThesecompoundsarecalledantimitoticdrugs,andhaveapplicationinmedicalpracticeasanticancerdrugsMicrotuble-associatedMicrotuble-associatedproteinsMAPsmodulateMTstructure,assembly,andfunctionMotorNonmotorTau:Inaxon,causeMTstoformtight

MAP2:Indendrites,causeMTstoformlooserTheTheimportanceofMAPsforneuriteLikeLikeLikeOrganizationOrganizationofMTbundlesbyMAPs.SpacingofMTsdependsonMAPsInsectInsectcellInsectcellFromJ.Chenetal.1992.Nature360:TheTheeffectsofproteinsthatbindtoMT(A)The(A)ThetransitionbetweenMtgrowthandMtshrinkingiscontrolledincellsbyspecial??蛋proteinshelptolocalizeMtinbuddingyeastFunctionsofMaintaincellMotorproteinsandintracellular（1）Motorproteins:3Kinesindependent- 600余头部具MT和ATP结合位点；迄600余CytoplasmicDyneindependent-MT(2/3HC+moreLC)14um/s;C端为马达结构域（结合ATP）;N端为易变尾部Axonemalarmdyneins:与纤毛鞭毛运动有关Myosindependent-IntracellularIntracellulartransportofmembrane-boundedvesicles,proteins:DirectionalityKinesinisaplus-enddirectedMTmotor年发现的驱动蛋白分子--常规驱动蛋白”oniolinin），只是相关蛋白超 中的一个成员，驱动蛋白相关蛋白iinldproin）超 简称为或LP（ineinlieproins）。根据 组序列分析，估计哺乳动物能产生种以上不同L。L的头部都含有相的氨基序列，反映出它们具有共同的进化祖先，并且在沿微管运动方具有相的作用。比较而言，P的尾部有较大变异，具有各种不同的序列，反映出不同的驱Hand-over-hand?????8nm,相当于?1.ComparisonofthemechanochemicalcycleskinesinandMotorMotorproteinsgenerateforcebycouplingATPhydrolysistoconformationalchanges.Dyneinisaminus-enddirectedmotorAxonemalandcytoplasimicdyneins胞质动力蛋白至少有两种移动的期间作为纺在有丝锤体定位和产力装置。移动的期间作为纺Mediate:动力蛋白激活蛋白复合体（dynactinIntracellularIntracellulartransportinnerveMtMtorganizationinfibroblastsandMovementMovementofpigmentgranules:colorTheTheplacementof MovementofmitoticspindleandCilia:Flagella:BendingCiliaandCilia:Flagella:BendingSizeSizeandlength:Thesamediameter,areoftenmuchCiliaryCiliaryMicrotubuleslidingcausescilia/flagellatoCrosslinksCrosslinksandIntermediatefilaments,IFsarethemostabundantandstablecomponentsofthecytoskeletonIFsassemblefromfibrousAssemblyCharacteristicsofMonomers:Monomers:FibrousAntiparallelAntiparalleltetramer:NoAlmostnoIFmonomerswithinButButIFsarestilldynamicpolymersintheservesasservesasadiagnostictoolinIFproteinsaretissue- Functi