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Basalbodystructure第1页C.CharacteristicsofMTassemblyDynamicinstabilityduetothestructuraldifferencesbetweenagrowingandashrinkingmicrotubuleend.GTPcap;Catastrophe:accidentallossofGTPcap;Rescue:regainofGTPcap第2页WhythecentrosomecanactasMTOCStructureNocentriolesinPlantandfungi第3页ExperimentssupportingthatcentrosomeistheMTOCTreatcellwithcolcemidCytosolicMTsdepoly,exceptthoseincentrosomeRemovecolcemidTublinrepolyExplaI:MTOCnucleatepolyoftubulinsExplaII:MTOCgatherMTsincytosolcentrosome+TubulinsMT+TubulinsNoAB第4页MTarenucleatedbyaproteincomplexcontaining-tubulinThecentrosomeisthemajorMTOCofanimalcells第5页DrugsaffecttheassemblyofMTs(1)ColchicineBindingtotubulindimers,preventMTspolymerization(2)

TaxolBindingtoMTs,stabilizeMTsThesecompoundsarecalledantimitoticdrugs,andhaveapplicationinmedicalpracticeasanticancerdrugs第6页Microtuble-associatedproteins(MAPs)MAPsmodulateMTstructure,assembly,andfunctionKataninlikeproteinsMAPsTau:Inaxon,causeMTstoformtightbundlesMAP2:Indendrites,causeMTstoformlooserbundlesMAP1B:InbothaxonsanddendritestoformcrossbridgebetweenmicrotubulesControlorganization第7页第8页第9页MAPsMAP1A,MAP1B,MAP1CMAP2,MAP2cMAP3，MAP4Tau第10页第11页第12页第13页第14页TheimportanceofMAPsforneuriteformation第15页第16页第17页OrganizationofMTbundlesbyMAPs.SpacingofMTsdependsonMAPsInsectcellexpressingMAP2InsectcellexpressingtauFromJ.Chenetal.1992.Nature360:674第18页TheeffectsofproteinsthatbindtoMTends(A)ThetransitionbetweenMtgrowthandMtshrinkingiscontrolledincellsbyspecialproteins.(B)CappingproteinshelptolocalizeMtinbuddingyeastcell.第19页5.FunctionsofMTs1.Maintaincellshape第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页Fig.

10-31

Microtubuledynamicsinalivingcell.

Afibroblastwasinjectedwithtubulinthathadbeencovalentlylinkedtorhodamine,sothatapproximately1tubulinsubunitin10inthecellwaslabeledwithafluorescentdye.Note,forexample,thatmicrotubule#1firstgrowsandthenshrinksrapidly,whereasmicrotubule#4growscontinuously.(P.J.Sammaketal.,Nature

332:724-736)第36页细胞内物质运输第37页第38页MotorProtein1.KinesinFamily2.DyneinFamily第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页第49页第50页第51页第52页第53页第54页

染色体运动第55页第56页第57页第58页第59页第60页第61页第62页第63页Intermediatefilaments,IFsIFsarethemostabundantandstablecomponentsofthecytoskeleton第64页第65页Figure

10-13

Thedomainorganizationofintermediatefilamentproteinmonomers.

Mostintermediatefilamentproteinsshareasimilarroddomainthatisusuallyabout310aminoacidslongandformsanextendedalphahelix.Theamino-terminalandcarboxyl-terminaldomainsarenon-alpha-helicalandvarygreatlyinsizeandsequenceindifferentintermediatefilaments.第66页Figure

10-14.

Acurrentmodelofintermediatefilamentconstruction.

第67页Figure

10–16.

Electronmicrographsoftwotypesofintermediatefilamentsincellsofthenervoussystem.

(A)Freeze-etchimageofneurofilamentsinanervecellaxon,showingtheextensivecross-linkingthroughproteincross-bridges.(B)Freeze-etchimageofglialfilamentsinglialcellsillustratingthatthesefilamentsaresmoothandhavefewcross-bridges.(C)Conventionalelectronmicrographofacross-sectionofanaxonshowingtheregul