蛋白质分选下培训讲学

Chapter7ProteinsortingII------free-ribosomesystemsecretorypathway

1.1SynthesisandTargetingofMitochondrial线粒体具有1000多种蛋白质，其自身合成的仅十余种，因此大量蛋白质是在细胞质中合成的。MatrixOutermembraneIntermembranespaceCrosssectionofmitochondrionInnermembraneMitochondrialProteinsThatAreSynthesizedintheCytosolProteinsAreTargetedtoSub-mitochondrialCompartmentsProteinimportintomitochondriaProteinTransportintoInnerMembraneandIntermembraneSpaceRequiresTwoSignalSequences线粒体转运与叶绿体非常相似1.2SorttoChloroplastCompartment叶绿体蛋白转运运输机理与线粒体的相似。如：•都发生后转译；•每一种膜上有特定的转位因子；•具有接触点（contactsite）；•需要能量，同样利用ATP和质子动力势；•前体蛋白N端有信号序列，使用后被信号肽酶切除。•但两者的蛋白质转运体系中除了某些hsp分子相同外，转位因子复合体是不同的。Importofrubiscosmall(S)subunitsintothechloroplaststroma

转运肽内囊体膜蛋白转运需要两段信号1.3SynthesisandTargetingofPeroxisomeProteins

核基因合成，后转运方式运输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):核糖核蛋白颗粒ProteincomponentofRNPcontainsanuclearexportsignal(NES)thatisrecognisedbyexportproteinsmRNAisboundbyhnRNPonlyafterfullysplicedsoonlymatureRNAisexportednuclearRNAandproteinexport

◆mRNAexport●核内不均一核糖核蛋白(heterogeneousribonucleoprotein,hnRNP)