Chapter 9 Cytoskeleton-2017ZF (1)(1).pptVIP免费

19.cellcytoskeleton2Cytoskeleton(细胞骨架):thenetworkcomposedoffibroid(纤维状)proteinsineukaryoticcells,includesthemicrotubule(微管),microfilament(微丝)andintemediatefilament(中间纤维或中间丝).Generalcytoskeleton:cytoplasmicskeleton(胞质骨架),nuclearmatrix（核骨架或核基质）andcellmembraneskeleton（细胞膜骨架）.3aroundthenucleusinastar-likecytoplasmicarraytheinnerfaceoftheplasmamembranethroughoutthecytoplasm柔软束状或网状柔软,绳状长直坚硬Cytoplasmicskeleton(胞质骨架)4OUTLINE◆MICROTUBULES◆MICROFILAMENTS◆INTERMEDIATEFILAMENTS51.Microtubule(MT)1)MorphologicStructure◆long,hollow,cylindricalstructures◆outerdiameterof25nm,◆innerdiameterof14nm◆wallthicknessofapproximately5nm◆lengthbeingvariable62)Chemicalcomponent◆Themicrotubulesmainlyconsistoftwotypesoftubulin(微管蛋白)molecules：α-tubulinandβ-tubulin；●eachαorβmonomerhasabindingsiteforamoleculeofGTP.TheGTPontheα-tubulinisneverbehydrolyzed.Thenucleotideontheβ-tubulinmaybeineithertheGTPortheGDPform,anditisexchangeable.●otherbindingsitesfordivalentcation（Mg2+）andspecificdrugs.73)Assemblyofmicrotubulesαβheterodimersof8nminlength13条原纤维纵向排列组成微管的壁微管的形成GTP帽(GTPCap)(片状结构)protofilament(原纤维或原丝);8(1)PeculiaritiesofMTassembly◆self-assembly◆Structuralpolarity--eachprotofilament:tubulindimerswithα-andβ-tubulinalternating--Tubulinsubunitsassemblehead-tailtogenerateprotofilaments--(+)endassemblesmorerapidly“+”端(plusend)和“-”端(minusend)9◆Dynamicpeculiarities----Dynamicinstability(动态不稳定性):Thisrapidinterconversionbetweenagrowingandshrinkingofmicrotubule.有丝分裂前期和末期发生10----Treadmilling(踏车现象--轮回现象):aphenomenonofdynamicequilibriumthattheplusendgrowswhiletheminusendshrinksduringelongationofmicrotubules.Dynamicstability11Dynamicinstabilityandtreadmilling:与反应体系中游离α、β二聚体的浓度变化有关theconcentrationofdimers＞Cctheconcentrationofdimers＜Cc◆Dynamicinstabilityandtreadmillingaidrapidcytoskeletalrearrangement◆Cc(Criticalconcentrationoftubulindime...