蛋白質分選下培訓講學

Chapter7ProteinsortingII------free-ribosomesystemsecretorypathway

1.1SynthesisandTargetingofMitochondrial線粒體具有1000多種蛋白質，其自身合成的僅十余種，因此大量蛋白質是在細胞質中合成的。MatrixOutermembraneIntermembranespaceCrosssectionofmitochondrionInnermembraneMitochondrialProteinsThatAreSynthesizedintheCytosolProteinsAreTargetedtoSub-mitochondrialCompartmentsProteinimportintomitochondriaProteinTransportintoInnerMembraneandIntermembraneSpaceRequiresTwoSignalSequences線粒體轉運與葉綠體非常相似1.2SorttoChloroplastCompartment葉綠體蛋白轉運運輸機理與線粒體的相似。如：?都發(fā)生后轉譯；?每一種膜上有特定的轉位因子；?具有接觸點（contactsite）；?需要能量，同樣利用ATP和質子動力勢；?前體蛋白N端有信號序列，使用后被信號肽酶切除。?但兩者的蛋白質轉運體系中除了某些hsp分子相同外，轉位因子復合體是不同的。Importofrubiscosmall(S)subunitsintothechloroplaststroma

轉運肽內囊體膜蛋白轉運需要兩段信號1.3SynthesisandTargetingofPeroxisomeProteins

核基因合成，后轉運方式運輸C-andN-TerminalTargetingSequencesPTS1PTS21.4ProteinsorttonucleusThenuclearporecomplex0.1um

Sideviewofnuclearpore1.4.1Nuclearproteintransportmechanism

◆nuclearlocalizationsignals,NLS◆nuclearexportsignals,NES◆importin◆exportinMechanismofproteinimportProteinsselectedforimportintonucleushaveanuclearlocalizationsignal(NLS)e.g.-Pro-Pro-Lys-Lys-Lys-Arg-NLSisrecognizedbycytosolicnuclearimportreceptorswhichbindtonuclearporefibrilsextendingintocytosolPoreopensandproteinplusimportreceptorenternucleus.Importreceptorexportedforre-useNuclearlocalizationsignals

Nuclearlocalisationsignal(NLS)Nuclearlocalizationsignals

Nucleoplasminlabelandinjection

NucleoplasminlocationeffectMechanismoftransportthroughnuclearporesNLSneednotcutaftertransport

NuclearimportProteintransportbynucleusporecomplexTransportisselectiveRestricttransportparticleRequireenergyexpendituresaturateddynamicTransportisdoubledirectionImportandexport1.4.2MechanismofexportfromnucleusMostoftrafficmovingoutofnucleusconsistsofdifferenttypesofRNAmoleculesRNAmovesthroughnuclearporeascomplexofribonucleoprotein(RNP):核糖核蛋白顆粒ProteincomponentofRNPcontainsanuclearexportsignal(NES)thatisrecognisedbyexportproteinsmRNAisboundbyhnRNPonlyafterfullysplicedsoonlymatureRNAisexportednuclearRNAandproteinexport

◆mRNAexport●核內不均一核糖核蛋白(heterogeneousribonucleoprotein,hnRNP)