細(xì)胞生物學(xué)-ru-第5章通訊

CHAPTER細(xì)胞通CELL1BASICCHARACTERISTICSOFCELL-SIGNALINGGPROTEINCOUPLEDSIGNALINGVIAENZYME-LINKEDRECEPTORSANDSIGNALINGCELL2細(xì)胞通訊：Cell細(xì)胞通訊：Cell信號出傳遞消決信息感信號出傳遞消決執(zhí)行功執(zhí)行功 細(xì)胞通訊：Cell 胞生理反應(yīng)/或引起活4CellCellCommunicationCell信號的產(chǎn)生及傳synthesisofsignalmoleculeSignalTransduction：signalrecognition

Signalrecognition5SIGNALINGFourTypesofCellCell-SurfaceReceptorsFallintoThreeMainClassesTheBasicCellSignalingFourTypesofCellContact-dependent:don’tneedsecretedPapacrine:tonearbyNeuronalEndocrine:tolongSignalcanactoverlongorshortrange.FromBruceAlbertsetal.,MolecularBiologyofTheCell(5thFromEssentialCellBiology(?GarlandScienceFromEssentialCellBiology(?GarlandScience.1CellSignalingandSignal不依賴于細(xì)胞接觸依賴于細(xì)胞接觸Signalrecognitionrecognition .2SignalRecognitionand受體（receptor）：任何能夠與信號分子結(jié)合受體（receptor）：任何能夠與信號分子結(jié)合CellsurfacereceptorsfallintothreebasicAnion-channel-coupledopensorclosesinresponsetobindingofitsextracellularsignalmolecule.Thesechannelsarealsocalled‘transmitter-gatedionchannelsFromBruceAlbertsetal.,MolecularBiologyofTheCell(5thG-protein-coupledreceptor:WhenaG-coupledreceptorbindsextracellularsignalmolecule,thesignalispassedfirsttoGTP-bindingprotein(Gprotein)thatisassociatedwiththereceptor.TheactivatedGproteinthenleavesthereceptorandturnon enzyme(orionchannel)inthemembraneFromBruceAlbertsetal.,MolecularBiologyofTheCell(5thEnzyme-coupledreceptors:Anenzyme-linkedreceptorbindsitsextracellularsignalmolecule,switchingonanenzymeactivity,eitherattheotherendoftheenzymeorotherassociatedenzymeFromBruceAlbertsetal.,MolecularBiologyofTheCell(5thCell-surfaceCell-surface（受體本身就是離子通道的一部分（GTP結(jié)合的調(diào)節(jié)蛋白偶聯(lián)（受體本身就是酶，又稱催化受體IntracellularIntracellularTwoTwomotifs,twobindingGenerationofconditionalknockoutSignalrecognition5.1.3Signal5.1.3Signal信號Manyintracellularsignalingproteinsa Signalingbyphosphorylation:signalingproteinsarebytheadditionofaphosphategroupbyproteinkinase,andinactivatedbyremovalofthephosphatebyproteinphosphatase.Proteinkinasephosphatesserine/threonine(calledser/thrkinase)ortyrosine(calledtyrosinekinase)SignalingbyGTP-bindingprotein:aGTP-bindingsignalingproteinisinducedtoexchangeitsboundGDTforGTP(i.e.addsaphosphatetotheprotein).ThehydrolysisoftheboundGTPtoGDPThenswitchestheproteinoffSignaltransductionpathwayconsistingproteinkinasesandproteinProteinkinase2isactivatedbyproteinkinase1.Onceactivated,proteinkinase2phosphorylatesproteinkinase3,activatingtheenzyme.Proteinkinase3thenphosphorylatesatranscriptionfactor,increasingitsaffinityforasiteontheDNA.BindingofatranscriptionfactortotheDNAaffectsthetranscriptionofthegeneinquestion.Eachoftheseactivationstepsinthepathwayisreversedbyaphosphatase.FromGeraldKarp,CellandMolecularBiology-conceptsandexperiments(6thTheregulationofamonomericFromBruceAlbertsetal.,MolecularBiologyofTheCell(5th

GTPase-activatingproteins(GAPs)inactivatetheproteinbystimulatingittohydrolyzeitsboundGTPtoGDP.Guaninenucleotideexchangefactors(GEFs)activatetheinactiveproteinbystimulatingittoreleaseitsGDP;NotethattheconcentrationofGTPincytosolis10timesgreaterthantheconcentrationofGDP,theproteinrapidlybindsGTPonceitejectsGDPandistherebySecond第一信使：細(xì)胞外部信第二信使：由細(xì)胞表面受體轉(zhuǎn)換而來的細(xì) 信號。第一信同其膜受體結(jié)合后最早在胞膜內(nèi)側(cè)或胞漿中出現(xiàn)的僅在細(xì)起作用的信號分子；能啟動或調(diào)解細(xì)胞內(nèi)稍晚出現(xiàn)的細(xì)胞應(yīng)答SignalTransductionataTypesofReceptor-EffectorSignalrecognition ExtracellularsignalscanactslowlyorFromEssentialCellBiology(?GarlandScienceSignalTheBasicCellSignalingTwodifferenttypesofsignaltransductionpathways:oneinwhichasignalingpathwayisactivatedbyadiffusiblesecondmessengerandanotherinwhichasignalingpathwayisactivatedbyrecruitmentofproteinstotheplasmamembrane.Mostsignaltransductionpathwaysinvolveacombinationofthesesignalingpathwaysarenottypicallylineartracksasdepictedhere,butarebranchedandinterconnectedtoformacomplexweb.FromGeraldKarp,CellandMolecularBiology-conceptsandexperiments(6th5.2GProtein-coupledGPCR－最具潛力的藥2006NatureReviewDrug

TrulyuniqueSmallMajor sin4majortypesofdrug nuclearreceptors，ligand-gatedorvoltage-gatedionchannels2006全球銷量前10名的藥(USD百萬1HMG-CoA2Advair,345Jul-6Johnson&Johnson,MitsubishiTanabeTNFα7Nov-8EliLillyand多種GPCR,Sep-9血管緊張素受體Johnson&等G-蛋白組成一般由三個亞基組成分別叫α、β、γ,β、γ兩亞基通常緊密結(jié)合在一起,只有在蛋功能位點點;②鳥苷三磷酸水解酶(GTPase)活性③ADP-核糖化位點CyclingofG

GDI（鳥苷解離抑制蛋白（鳥苷交換因子（GTPase激活蛋白Bindingofsignalmoleculetoreceptorcausestheconformationchangeofthisreceptor,whichinturnalterstheconformationoftheGThealterationoftheαsubunitofGproteinallowsittoexchangeitsGDPtoGTPThiscausestheGproteintobreakupintotwoactivatecomponents-αsubunitandaβγcomplex,bothcanregulatetheactivityof proteinsintheplasmamembraneFromEssentialCellBiology(?GarlandScienceClassificationofGG-proteinRegulationofIone.g.GPCRactivationtoopeningofK+channelsintheplasmamembraneofheartmusclecellsactivatedcomplexbindsandopensaK+inactivationoftheasubunitbyhydrolysisofitsboundGTPreturnstheGproteintoitsinactivestate,allowingtheK+channeltocloseFromEssentialCellBiology(?GarlandSciencePKAPKAphosphorylate residueson PKAFunction?phosphorylatesDiscoveryofcAMP第二信使DiscoveryofcAMP第二信使EarlW.DiscoveryofcAMP第二信使EarlW.DiscoveryofG1994年醫(yī)學(xué)和生理 獎獲得Martin

AlfredG.DiscoveryofGDiscoveryofGMartinDiscoveryofGDiscoveryofGPKAFunctioncAMPcAMP通過磷酸二酯酶將cAMP降解,形成5'-通過抑制型的信號作用于Ri后通過Gi起作cAMP信號的抑制cAMP信號的抑制毒素對cAMP信號途徑的影霍亂:無痛性腹瀉,“米泔水樣”瀉途徑：污染的水源或未 食物如海產(chǎn)品、蔬菜經(jīng)口攝入霍亂毒素(cholera能把NAD+上的NAD-核糖轉(zhuǎn)移到Gs蛋白的α亞基上，使G蛋白核化(ADP-ribosylation),這樣將抑制α亞基GTPase活性……毒素對cAMP信號途徑的影百日咳：百日咳桿菌所致的急性呼吸道傳染病，陣發(fā)性痙咳及陣咳終末出現(xiàn)的雞鳴樣吸氣性吼聲。多見于五歲以下的小兒?；颊呤俏ㄒ坏膫魅驹?，通過飛沫傳染。百日咳毒素 couch作用機理同霍亂毒素相同，但是使Gi蛋白進行ADP核糖化 Gi亞基活化，其結(jié)果也是使cAMP的濃度增加(Phosphatidylinositol路也稱IP3、DAG、Ca2+信號通路,或稱為PKC(ProteinkinaseC)系統(tǒng)PKCPKCPKCFunctionCalciumionsplayasignificantroleinaremarkableofcellularactivities,includingmusclecontraction,division,secretion,endocytosis,fertilization,transmission,metabolism,andcell oleculeofcalmodulincontainsfourbindingsitesforcalcium.CalmodulindoesnothavesufficientaffinityforCa2+tobindtheioninanon-stimulatedcell.If,however,theCa2+concentrationrisesinresponsetoastimulus,theionsbindtocalmodulin,changingtheconformationoftheproteinandincreasingitsaffinityforavarietyofeffectors.62Ca2+andCa2+/Calmodulindependentprotein (PKC)IP3/DAG/Ca2+信號的終 DAGDAG只是由PIP2水解得到的暫時性產(chǎn)物, 只有幾秒鐘,靠兩種方式進行降解:被DAG磷酸激酶磷酸化,生成磷脂酸(PA),PA被轉(zhuǎn)化為CMP磷脂酸,再與肌醇作用合成磷脂肌醇(PI)。DAG被DAG酯酶水解生成單脂酰甘油,進一步水解(PKCIP3DAG/Ca2+信號的終IP3作用的終IP3的水在5’磷酸酶的作用下,水解為I(1,4)P2,并一步水解成肌醇。5’在胞漿的肌醇磷酸脂3-激酶的作用下IP3被磷酸化成I(1,3,4,5)P4 (PKC)IP3/DAG/Ca2+信號的終 Ca2+信號解IP4參與打開細(xì)胞質(zhì)膜上的 通道,使細(xì)胞質(zhì)中Ca2+較為持久地增胞內(nèi)Ca2+濃度持久地升高,可激活Ca2+-ATP酶（質(zhì)膜、內(nèi)質(zhì)網(wǎng)膜的鈣泵），從而降低胞質(zhì)中的Ca2+，使胞質(zhì)中的Ca2+迅速恢復(fù)到基態(tài)水平(10-7 M),并使活性5.3Enzyme-linked不需要信號偶聯(lián)蛋白(G-蛋白),而是通過受體自身的酪該通路對信號的反應(yīng)比較慢(通常要幾小時)，并且需要許多細(xì)胞內(nèi)的轉(zhuǎn)換步驟通常與細(xì)胞相關(guān)。Enzyme-linkedEnzyme-linked酪氨酸激酶偶聯(lián)受體(tyrosinekinase-linked內(nèi)源酶促活性受體(receptorswithintrinsicactivity鳥苷環(huán)化酶受體(Receptorguanylyl酪氨酸磷酸酶受體(Receptoroftyrosine酪氨酸激酶受體(Receptortyrosine絲氨酸/蘇氨酸激酶受體(Receptorkinase)receptorswithintrinsicenzymatic鳥苷環(huán)化酶受體(Receptorguanylyl心房鈉受體本身是鳥苷環(huán)化結(jié)構(gòu)cGMP為第二信cGMP依賴性蛋白激酶第二信使cGMPcGMP也是GPCR信號通路中的第二信使：光受體視紫紅G蛋白：轉(zhuǎn)導(dǎo)cGMP特異性的磷酸二酯PKG(cGMPdependentproteincGMP的靶蛋白，是依賴于cGMP的蛋白激酶催化亞同cGMP結(jié)合的調(diào)組蛋白(H1H2A磷酸化酶激糖原合膽固醇脂水解酪氨酸激酶受體(Receptortyrosinekinase受體本身是酪氨酸激結(jié)構(gòu)胞外配體結(jié)合結(jié)構(gòu)胞內(nèi)RTK結(jié)構(gòu)靶蛋白酪氨酸殘基磷細(xì)胞生長因子受體：EGF，PDGF，M-CSF，IGF1，RTK單體無受體二聚體：信號分子二聚體或構(gòu)象改形成信號傳導(dǎo)復(fù)合細(xì)胞內(nèi)信號傳導(dǎo)蛋白結(jié)合并激 酪氨酸激酶受體(Receptortyrosinekinase，胰島素

四聚激活自磷酸胰島素受體底物（IRS）磷酪氨酸激酶受體(Receptortyrosinekinase胰島素

SH結(jié)構(gòu)域：Src同源結(jié)構(gòu)SH2，SH2是一種與磷酸酪氨酸基序具有高親和性的結(jié)合位（氨基酸序列IRS1-酪氨酸激酶受體(Receptortyrosinekinase，EGF受糖蛋三個結(jié)EGF結(jié)合結(jié)跨膜蛋白激酶活性受體激活：C端有幾個含酪氨酸殘基的自身磷酸化部與靶蛋白SH2結(jié)酪氨酸激酶受體(Receptortyrosinekinase a，是原 表達(dá)產(chǎn)介導(dǎo)外信號→受PKK(MEK)→MAPK 酪氨酸激酶受體(Receptortyrosinekinase，單體GTP弱GTP酶活激活：鳥苷交換因子-GEF釋放失活：GTP酶激活蛋白-Grb2和Sos蛋

Enzyme-linkedGrb2和Sos蛋Grb2生長因子受體結(jié)Sos鳥苷酸釋放蛋白：一種GEF,Ras激活蛋白Enzyme-linked生長因子信號經(jīng)的級聯(lián)MAPKKKMAP激酶酶的激酶-MAPKKMAP激酶的激-MAPKMAP激MAP: 原活化白Ras突變 proteinthatcanbeactivatedbyNOisguanylTheactivatedcyclasecatalyzestheproductionofcGTPfromsignaltransductionpathwaythatoperatesbymeansofNOandcyclicGMPthatleadstothedilationofbloodFromGeraldKarp,CellandMolecularBiology-conceptsandexperiments(6thCellsignalingandtheFunctionoffocalIntegrinsignalingdependsonfocaladhesionkinase(FAK)RhofamilyregulationoftheactinFunctionoffocalFocaladhesions(cell–matrixadhesions)arespecifictypesoflargeassemblies.ItisthemechanicallinkagestotheThemechanical-structuralfunctionoffocaladhesion,whichiscarriedoutbyactinfilamentsandassociatedproteinsSignalingfunctionfromsurfacenucleus(wheretheystimulatethetranscriptionofgenesinvolvedincellgrowthandproliferation),whichiscarriedoutbytyrosinekinase(SrcandFAK)Whenintegrinsclusteratcell-matrixcontacts,FAKisrecruitedbyanchorprotinessuchastalinorIntegrinsignalingdependsonfocaladhesionkinaseFocaladhesionsconcentrateanddirectnumeroussignalingproteinsatsitesofintegrinbindingSignalpathwaythatleadtotheassemblyofthefibersofafocalRhoisinvolvedinregulatingtheorganizationofthecell’sactincytoskeleton.ModelforsignalingfromtheFAKprotein-tyrosinekinase.BindingofintegrinstotheextracellularmatrixstimulatesFAKactivity,leadingtoitsautophosphorylation.SrcthenbindstotheFAKautophosphorylationsiteandphosphorylatesFAKonadditionaltyr