大二上學期文件-細胞生物學chapter10cytoskeleton

110.cellcytoskeletonandcellmotility2Cytoskeleton(細胞骨架):thenetworkcomposedoffibroid(纖維狀)proteins

ineukaryoticcells,includesthemicrotubule(微管),

microfilament(微絲)andintemediatefilament

(中間纖維).General

cytoskeleton:cytoplasmicskeleton,nuclearmatrixandcellmembraneskeleton.3aroundthenucleusinastar-likecytoplasmicarraytheinnerfaceoftheplasmamembranethroughoutthecytoplasm柔軟束狀或網(wǎng)狀柔軟,繩狀長直堅硬Cytoplasmicskeleton4OUTLINE◆MICROTUBULES◆MICROFILAMENTS◆

INTERMEDIATEFILAMENTS51.Microtubules(MTs)1)MorphologicStructure◆long,hollow,cylindricalstructures◆outerdiameterof25nm,◆innerdiameterof14nm◆wallthicknessofapproximately5nm◆lengthbeingvariable62)Chemical

component◆Themicrotubulesconsistoftwotypesoftubulin(微管蛋白)molecules：α-tubulin

andβ-tubulin；●eachαorβmonomerhasabindingsiteforamoleculeofGTP.TheGTPontheα-tubulinisneverbehydrolyzed.Thenucleotideontheβ-tubulinmaybeineithertheGTP

ortheGDPform,anditisexchangeable.●otherbindingsitesfordivalentcationandspecificdrugs.73)Assemblyofmicrotubulesαβheterodimersof8nminlength13條原纖維縱向排列組成微管的壁微管的形成GTP帽(GTPCap)(片狀結(jié)構(gòu))(原纖維)8(1)PeculiaritiesofMTassembly◆

Structuralpolarity--eachprotofilament:tubulindimerswithα-andβ-tubulinalternating--Tubulinsubunitsassemblehead-tailtogeneratefilaments--(+)endassemblesmorerapidly“+”端(plusend)和“-”端(minusend)9◆Dynamic

peculiarities

----Dynamicinstability(動態(tài)不穩(wěn)定性):Thisrapidinterconversionbetweenagrowingandshrinkingofmicrotubule,atsomefreesubunitconcentration.有絲分裂前期和末期發(fā)生10----Treadmilling(踏車現(xiàn)象--輪回現(xiàn)象):Ahomeostasis

phenomenonthattheplusendgrowswhilethe

minusendshrinksduringelongationofmicrotubules.11Dynamicinstabilityandtreadmilling:與反應(yīng)體系中游離α、β二聚體的濃度變化有關(guān)

◆Criticalconcentrationoftubulindimers(Cc,微管蛋白臨界濃度):theconcentrationatdynamicequilibriumbetweentubulindimersandMTtheconcentrationofdimers＞Cc

theconcentrationofdimers＜Cc◆Dynamicinstabilityandtreadmillingaidrapidcytoskeletalrearrangement12invivomicrotubuleassemblyMTOC(microtubuleorganizingcenters--微管組織中心):

generatinglocus(核心)ofreassemblyafterMTdepolymerizationininphysiologicalstatusorexperimentaltreatment.

(-)endpointstoMTOC，Basalbody(基體)andcentrosome(中心體)formtheorganizingcentersforthemicrotubules.中心體由中心粒和中心粒旁基質(zhì)組成在分裂間期，在核附近，在分裂期，在紡錘體兩極。13（樹突）中心粒胞質(zhì)微管軸絲微管（軸突）中心?；w只含一個中心粒植物細胞無中心體，其微管組織中心是核外被表面的成膜體（phragmoplast）14γ-tubulinring(γ-微管蛋白環(huán)）(+)end(-)endγ-tubulin通過與β

–tubulin蛋白相互作用幫助微管成核15(2)Factorsthataffectmicrotubuleassembly

Thecriticalconcentrationoftubulindimers,

GTP,

pH(最適6.9),temperature（37℃）,pressure,Ca2+,andaccessoryproteins,chemical

drugs16Theconcentrationoftubulinheterodimer,GTPcapmicrotubuleassemblyandGTPcapat(+)poleend17◆MAP(MicrotubuleAssociatedProtein,微管結(jié)合蛋白）

MAPshavetheMTbindingdomains,oneendbindingtoMT,otherendbindingto

adjacent

MT,cellmembraneorothercytoplasmicskeleton.

stabilizeMT18MAPs的功能◆使微管相互交聯(lián)形成束狀結(jié)構(gòu);◆促進微管的聚合;◆提高微管的穩(wěn)定性,防止微管的解聚?！糇鳛榉肿影l(fā)動機(Molecularmotor:convertchemicalenergyintomechanicalenergy)轉(zhuǎn)運細胞物質(zhì)的軌道;19Typesofmolecularmotors(分子發(fā)動機)◆Motorproteins(發(fā)動機蛋白)canbegroupedintothreebroadfamilies:●驅(qū)動蛋白(kinesins)家族

Tomovealongmicrotubules(從(-)端向(+)端的運輸)●動力蛋白(dyneins)家族

Tomovealongmicrotubules(從(+)端向(-)端運輸)●肌球蛋白(myosins)家族

Tomovealongmicrofilaments.20動力蛋白驅(qū)動蛋白tomovecellularcargoattachedtothemotor21◆Drugsspecifictomicrotubuleassembly--Colchicine(秋水仙素)andvinblastine(長春花堿)inhibitassemblyofmicrotubuleanddestroystructureofspindlebybindingtounpolymerizedtubulindimers

--Taxol(紫杉醇:紅豆杉屬植物中的一種復雜的次生代謝產(chǎn)物,促進微管聚合和穩(wěn)定已聚合微管的藥物)makethemicrotubulespolymerizedstable.224)Typesofmicrotubules◆Composition:●singlet（單管：13條原纖維)●doublet（雙聯(lián)管）●triplet（三聯(lián)管）spindleMTA(13)為完全微管B（10條），C(10)23◆stability(穩(wěn)定性):●unstablemicrotubules(短壽)●stablemicrotubules(長壽)245)FunctionsAsascaffold(支架)

：maintaincellshape

(protuberanceofcell,suchascivil,flagellaandaxone).25

localizationoforganellesERGCnucleus26Asthetracksoftheintracellularsubstancetraffic(魚的色素細胞)27作為驅(qū)動蛋白與動力蛋白運輸軌道神經(jīng)元細胞28FormationofmitoticspindleMTparticipateincellplateformation

inhigherplantcells.spindlepolekinetochoreMTshorteningAnaphase:spindlepolemovingoutward29Ascrucial

componentofbasalbodiesandcentrosome近基體30Movementofflagella(鞭毛)andcilia

(纖毛)鞭桿基體apairofsingle

microtubule“9+2”characteristicarrangementATPbindingsite中央鞘外動力蛋白臂flagella(鞭毛)orcilia：

consistofplasmamembraneandaxoneme(軸絲)31◆纖毛動力蛋白(ciliarydynein)●是多頭的動力蛋白●基部同A管相連●頭部同相鄰的B管相連●頭部具有ATP結(jié)合位點，能夠水解ATP。32◆Movementme