生化信號(hào)轉(zhuǎn)導(dǎo)1－生化

Signal-TransductionPathways

信號(hào)轉(zhuǎn)導(dǎo)通路(1)

鄭利民2008珠海

zhenglm@1.干細(xì)胞的分化2.植物的生長(zhǎng)發(fā)育是在環(huán)境因子的影響下正確進(jìn)行時(shí)空表達(dá)的過(guò)程3.信號(hào)受體反應(yīng):手觸摸就是刺激(信號(hào))，小葉合攏就是反應(yīng)。偶聯(lián)刺激到反應(yīng)之間的生化和分子途徑,就是這個(gè)反應(yīng)的信號(hào)轉(zhuǎn)導(dǎo)通路觸摸含羞草后,小葉合攏4.細(xì)胞信號(hào)轉(zhuǎn)導(dǎo)網(wǎng)絡(luò)的簡(jiǎn)單模式（信號(hào)輸入）（信號(hào)輸出）5.ImportantrolesofbiosignalingFunctionalintegrationofdistantorgans,tissuesandcellsrequirescommunication;Signalingisperhapsaprimalrequirementtorespondtoourenvironment;Thefoundationofanycomplexresponsepathwaylieswithcellularbiochemicals.BiosignalingIntercellular（細(xì)胞間）&Intracellular（細(xì)胞內(nèi)）6.常見(jiàn)四種類(lèi)型：Endocrine(內(nèi)分泌）Paracrine(旁分泌）Autocrine(自分泌）MembraneattachedproteinIntercellularsignaling

（細(xì)胞間信號(hào)）7.Fourschemesofintercellularsignaling(1)8.Fourschemesofintercellularsignaling(2)9.Intracellularsignaling

（細(xì)胞內(nèi)信號(hào)）10.IntracellularReceptor11.Electron-micrographofmacrophage(pink)attackingEscherichiacoli(green)12.M吞噬處理入侵細(xì)菌及提呈抗原的機(jī)制13.SignalTransductionPathway:Complicated14.FcR

CR3Ca++srcPI3kPKCMAPKRhoGTPasegelsolinArp2/3PLCPLDActinrearrangementPhagocytosis;OxidativeactivationSignals

forphagocytosisSignalReceptorAmplificationTransductionResponsessecondmessengers15.信號(hào)轉(zhuǎn)導(dǎo)要素：信號(hào)或配體,受體,信號(hào)放大(產(chǎn)生第二信使),應(yīng)答和反饋調(diào)節(jié)胞外 質(zhì)膜 胞內(nèi)16.PARTⅠ1Basiccharacteristicsofsignaltransduction2FourgeneraltypesofsignaltransducersPARTⅡ1Regulatorymechanisms2Somediseasescausedbydefectsinthebiosignalingpathways17.1Fourbasiccharacteristics:1.1Specificity1.2Amplification1.3Desensitization/Adaptation1.4Integration18.SpecificitySignalmoleculefitsbindingsiteonitscomplementaryreceptor;othersignalsdonotfit.thrombin19.Scatchardanalysisquantifiesthereceptor-ligandinteraction20.oftenshort-lived&lowconcentration21.Desensitization/Adaptation

ReceptoractivationtriggersafeedbackcircuitthatshutsoffthereceptororremovesitfromthecellsurfaceProducearapidandmajorcellularresponsetoatransientsignal22.IntegrationWhentwosignalshaveoppositeeffectsonametaboliccharacteristicsuchasconcentrationofasecondmessengerX,orthemembranepotentialVm,theregulatoryoutcomeresultsfromtheintegratedinputfrombothreceptors23.細(xì)胞存活細(xì)胞凋亡Thebalancebetweenpro-andanti-apoptoticgenes/signalsdeterminethecellfate細(xì)胞接受到“死亡信號(hào)”，不一定就會(huì)死亡若同時(shí)也接受到“生存信號(hào)”，就可繼續(xù)存活24.25.2.Fourtypesofsignaltransducers2.1GatedIonChannels

2.1.1Ligand-gatedionchannels 2.1.2Voltage-gatedionchannels2.2ReceptorEnzymes2.3GProtein–CoupledReceptors andSecondMessengers2.4SteroidReceptors26.Fourgeneraltypesofsignaltransducers27.WhyIonChannels?Restingpotential:Asymmetricion-distributionActingpotentialGatedIonChannels

Ligand-gatedionchannels Voltage-gatedionchannels28.Restingpotential29.IonConc.inMammalianCellsandSerum(mM）IonCytoplasmBloodSerumK+1404Na+12145Cl-4116proteincharges1389Mg+20.81.5Ca+2<0.00021.8WhyIonChannels:asymmetricion-distribution30.asymmetricion-distributionRestingpotential31.pumpandionleakchannelsCl

-leakchannel32.Actingpotential33.ActingpotentialVoltage-gatedNa+channels&K+channelsLigand-gatedionchannel:Bindingofsomesmallmoleculeforcesanallosterictransitioninprotein,open/closechannel.

acetylcholine(乙酰膽堿)receptorionchannel2.1.2Voltage-gatedionchannelAchargedproteindomainmovesrelativetothemembraneinresponsetoachangeintransmembraneelectricalpotential.

(voltage-gatedNa+，

Ca2+，K+channels)35.乙酰膽堿受體離子通道1AchACh36.BindingofAChtoRcauseconformationalchange.AsM2helicestwistslightly,theLeuresidues(yellow)rotateawayfromthechannelandarereplacedbysmallerpolarresidues(blue).Thisgatingmechanismopenschannel,allowingpassageofCa,Na,orK乙酰膽堿受體離子通道2Closed Open37.Voltage-gatedNa+channels138.Voltage-gatedNa+channels239.2.Fourtypesofsignaltransducers2.1GatedIonChannels

2.1.1Ligand-gatedionchannels 2.1.2Voltage-gatedionchannels2.2ReceptorEnzymes2.3GProtein–CoupledReceptors andSecondMessengers2.4SteroidReceptors40.

2.2ReceptorenzymesAligand-bindingdomain(胞外)andanenzymeactivesiteoncytosolicside,connectedbyasingletransmembranesegment.CommonlyakinasethatphosphorylatesTyrresiduesinspecifictargetproteins（insulinreceptor）Other:synthesizethei.c.secondmessengercGMPinresponsetoex.c.signals

(thereceptorforatrialnatriureticfactor)41.Activationofreceptortyrosinekinases42.InsulinreceptortyrosinekinaseInsulinstructure43.Insulinreceptorbindsinsulinandundergoesautophosphorylationonitscarboxyl-terminalTyrresidues.InsulinreceptorphosphorylatesIRS-1onitsTyrresidues.SH2domainofGrb2bindstoP–TyrofIRS-1.SosbindstoGrb2,thentoRas,causingGDPreleaseandGTPbindingtoRas.ActivatedRasbindsandactivatesRaf-1.Raf-1phosphorylatesMEKontwoSerresidues,activatingit.MEKphosphorylatesERKonaThr&aTyrresidue,activatingit.ERKmovesintothenucleusandphosphorylatesNucleartranscriptionfactorssuchasElk1,activatingthem.PhosphorylatedElk1joinsSRFtostimulatethetranscriptionandtranslationofasetofgenesneededforcelldivision.44.Activationofglycogensynthasebyinsulin45.Regulationofbloodglucoselevel46.

ReceptorforatrialnatriureticfactorTwotypes(isozymes)ofguanylylcyclasethatparticipateinsignaltransduction.47.2.Fourtypesofsignaltransducers2.1GatedIonChannels

2.1.1Ligand-gatedionchannels 2.1.2Voltage-gatedionchannels2.2ReceptorEnzymes2.3GProtein–CoupledReceptors andSecondMessengers2.4SteroidReceptors48.2.3GPCRandSecondmessengersThreeessentialcomponents:1.aplasmamembranereceptorwithseventransmembranehelicalsegments2.anenzymeintheplasmamembranethatgeneratesanintracellular2ndmessenger3.aguanosinenucleotide–bindingprotein(Gprotein)49.ThreeessentialcomponentsofGProtein–CoupledReceptors50.51.AproteinbindsGuaninenucleotides(GDP,GTP);activatedinGTP-form,inactivatedinGDP-formIntegralmembraneprotein,heterotrimers();Havesimilar&subunits,butdifferin-subunitWhenG-proteinisactivated,thesubunitdissociatestointeractwithanenzymesthatgeneratesecondmessengers(e.g.cAMP)Others:smallG-proteins(~20-25kDa),e.g.Ras,Rho,Rac,etc,arenotmembranebound.Gprotein(GTP-bindingprotein)52.Gprotein(discovery)M.Rodbell:atransducerprovidedthelinkbetweenreceptorandamplifier.A.G.Gilman:identify&purifytheGprotein.System:MutatedlymphomacellscontaininganormalreceptorandcAMP-generatingenzyme,wasyetunabletorespond(producecAMP),sinceitlackedthetransducermutatedcellnormalcell53.NobelPrizeinPhysiologyandMedicine1994"fortheirdiscoveryofG-proteinsandtheroleoftheseproteinsinsignaltransductionincells"AlfredG.Gilman

1941-MartinRodbell

1925-199854.“ON-OFF”switchisregulatedbyGTPorGDPboundform.AllG-proteinshasintrinsicGTPaseactivity,releasePiandinactivated.Activation:releaseofGDPandreplacedbyGTP55.Twomajorsystems:2.3.1THEPKASYSTEM (cAMPasthesecondmessenger)

The-AdrenergicReceptorSystem2.3.2THEPKCSYSTEM

(DAG,IP3andCa2+asthesecondmessengers)56.TheassociationofactiveGs

withadenylylcyclasestimulatesthecyclasetocatalyzecAMPsynthesisAdenosine3’,5’-cyclicmonophosphate(cAMP)57.synthesizedinadrenalmedulla;belongstocatecholamines(兒茶酚胺）;targetcellsincludeliver,skeletalmuscle,heartmuscleandadipose;releasedinresponsetoacutestressEpinephrine腎上腺素signal58.Epinephrine腎上腺素signalingpathwaycAMP59.Epinephrine腎上腺素signalingpathway(2)60.ActivationofcAMP-dependentproteinkinase(PKA)InactivePKA:Regulatory(R)subunits:auto-inhibitorydomainsburiedcatalytic(C)subunits:substrate-bindingsitesblockedbyRsubunitsRsubunits:autoinhibitorydomainsburiedActivePKACsubunitsopensubstratebindingsites61.AcatalyticsubunitofPKAATPPotentinhibitorpeptide(PKI):Arg-Arg-Gln-Ala-Ile(consensussequencerecognizedbyPKAexceptAla)62.Epinephrinetriggersaseriesofreactionsinhepatocytesinwhichcatalystsactivatecatalysts,resultingingreat“amplification”ofthesignalx分子10,000x分子63.PKAregulatesanumberofenzymesTheproteinsphosohorylatedbyPKAsharearegionofsequencesimilarityaroundtheSerorThrresiduethatundergoesphosphorylation,asequencethatmarksthemforregulationbyPKA.ThecatalyticsiteofPKAinteractswithseveralresiduesneartheThrorSerresidueinthetargetprotein,whichdefinethesubstratespecificity.64.65.DesensitizationofthePKAsystem1desensitizingβ-AdrenergicReceptor2degradingthesecondmessager66.GsbgrecruitsbARKtothemembrane,whereitphospho-

SerattheC-terminusofRecpt.barrbindstothepi-C-terminusofRecpt.Receptor-arrestincomplexentersthecellbyendocytosis.67.β-Arrestinuncouplesr