细胞生物学-微管微丝10.filament and intermediate

10.3Microfilamentsareapproxima y8nm andcomposedofactin(肌动蛋白).Microfilamentsconsistoftwostrandsofactin woundaroundeachotherinadouble (由双股肌动蛋白丝以螺旋的形式组成的纤维MorphologyandStructureunit:threebindingoneATP-bindingtwoactin-bindingprotein(肌动蛋白结合蛋白)bindingsites.F-actin(F-肌动蛋白fibrosadouble (F-肌动蛋白呈双股螺旋状,直径为8nm。MicrofilamentAssemblyandDisassemblyFunctionsofActinisanATPase,justastubulinisaGTPase,andtheroleofATPinactinassemblyissimilartothatofGTPinmicrotubuleassembly.Assemblynucleationelongation动steadystate(稳定状动assemblyG-肌动蛋白临界浓Ca2+:F- G-actinATP,Mg2+,K+/Na+:G- F-微丝的动态性polarity:+(ATP),-treadmilling(踏车现象cytochalasinsB(细胞松弛素B)：同微丝的结合，并引起微丝的解聚phalloidin(鬼笔环肽)：同微丝结丝 Typesandmonomer-sequesteringprotein(单 蛋白bindtoG-actinandpreventthemfromendingblockingprotein(末端阻断蛋regulatethelengthofactinfilamentsbybindingtotheoneorthetwoendofactinfilaments(F-actin),i.e. alterthethree-dimensionalorganizationof filaments.bindtoanexistingactinfilamentandbreakitintotwomaketheplasmamembranecontractinthenon-musclecell10.3.3.3Myosin(肌球蛋白):微丝 蛋consistofoneheavychainandseverallightchains,andformthree containsasitethatbindsanactinfilamentandasitethatbindsandhydrolyzesATPtodrivethemyosinmotor. 颈部通过同钙调素或类似钙调素的调节轻链亚基的结 containsa whether bindsthemembraneordeterminedbytheirmyosinⅠ:myosinⅤ:myosinⅡ:musclecytoplasmMovementmechanismofmyosin：slidingMuscleStructureofskeletalmusclemusclefibers(肌纤维myofibrils(肌原纤维IbandandAband(I带与A带Iband(isotropicbandI带):lightAband(anisotropicband,A带):darkZdisk(Z线):I带 较深的Hzone(HlightlystaininglocatedintheofAere肌节apairofIbandsAStructureofthickfilamentcomposeof250-300thinfilament细肌丝actin:约占肌原纤维的总蛋白的oneTmcontainssevenactin-bindingtroponin(Tn,肌钙蛋白 ,Tn-I,Tn-其他:肌联蛋白、伴肌动蛋Musclecontractionduringmuscle肌节几乎缩短AbandremainedessentiallyconstantinHbandandIbanddecreasedinwidthandthendisappearaltogether.Zlinesonbothendsofthe eremovedinwarduntiltheycontactedtheouteredgesoftheA(滑动丝模型Theshorteningof eredidnotresultfromtheshorteningofthefilaments,butrathertheirslidineroneanother.Theslidingofthethinfilamentstowardthecenterofthe erewouldresultintheobservedincreaseinoverlapbetweenthefilamentsandthedecreasedwidthoftheIandHbands.（细肌丝向肌 滑动，导 部分增加，I带和H的宽度缩小，肌节缩短。Ca2+functionsinthemuscleCa2+modulatemuscleRelax:Tmbindsevenactins,thenblockthemyosin-bindingsitesontheactinmolecules.Contract:Ca2+bindtoTn-C，alterthetropomyosin-bindingsitestotheactinmolecules,relievetheinhibitionofTmtoactin,exposethebindingsitetothemyosinhead.Ca2+和肌钙蛋白Tn-C的结合，改变原肌球蛋白同肌动蛋白的神经冲动引起肌细Ttubules(transversetubules,T管)∶motornervesignalsopentheCa2+channelbyTtubulesCa2+bind toTn-C，relievetheinhibitionofTmtoactin.myosinheadsbindtoactinandthecross-bridges(交联桥)利用ATP进行滑动，产

10.3.5Functionsofactinandmyosininthenon-musclecellcellcytoplasmicstreaming(胞质环流cellamoeboidmotion(变形运动cellcrawling(细胞爬行cytokinesis(胞 10.4IntermediatefilamentHaveadiameterof10nm,whichisintermediatebetweenthatofmicrotubulesandmicrofilaments由长的、似杆状的蛋白装配而

Structureandtypeof(角蛋白(波形蛋白(神经丝蛋白 Inhumans,IFsareencodedbyatleast50differentThepolypeptidesubunitsofIFscanbedividedintosixmajorclassesbasedontheirtissuedistribution. IntermediateFilamentAssemblyandDisassemblyeighttetramerstwistedintoa10.4.2.3Intermediatefilament-associatedprotein(IFAP,中间纤维结合蛋白)IFAPs能够将中间纤维相互交联Plectin(网蛋白)interactswithothercytoskeletalproteinsincludingspectrin(血影蛋白),microtubuleassociatedproteins,andlaminB.IFImpartmechanicalstrengthtoAttendcell

6IFOutsideInsidetheWhole713232Main思考1、简述微丝结合蛋白的类型和功3、简述Ca2+在肌收缩中的作5、简述中间纤维的类型，结构和功能6、比较三种细胞骨架的异同7、不同药物对微管和微丝的影G-

F-MicrofilamentdynamicSmoothmusclecell:redfluorescence---Actin-binding(凝溶胶蛋白 Filament-severingprotein(微丝切断蛋白(踝蛋(黏着(踝蛋((整联Membrane-bindingprotein(膜结合蛋Myosinsuperfamily白胰凝乳蛋白酶白?的 木瓜蛋白酶处理构Myosinmyosin双极性肌球蛋白II的装Stressfiberα辅肌动

细丝蛋(丝束(绒毛(微绒毛动微丝在细胞中的作动?Cytoplasmic（周细胞质Amoeboid(外质(内质动动动(胞 (肌纤维?(肌原纤维(肌节GeneralStructureofSkeletalandSmooth动Myofibrils MuscleSlidingFilament钙对肌肉收缩