《蛋白质分选》PPT课件

《《蛋白质分选》PPT课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Chapter7ProteinsortingII------free-ribosomesystemsecretorypathway1.1SynthesisandTargetingofMitochondrial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。线粒体前体蛋白质在在运输以前，以未折叠的形式存在，N端有一段信号序列称为导肽或引肽，完成转运后被信号肽酶（signalpeptidase）切除，就成为成熟蛋白，这种现象就叫做后转译（posttranslation）。信号肽的特点是：–多位于肽链的N端，由大约20个氨

2、基酸构成；–形成一个两性α螺旋，带正电荷的氨基酸残基和不带电荷的疏水氨基酸残基分别位于螺旋的两侧；–对所牵引的蛋白质没有特异性要求。MatrixOutermembraneIntermembranespaceCrosssectionofmitochondrionInnermembraneMitochondrialProteinsThatAreSynthesizedintheCytosolProteinsAreTargetedtoSub-mitochondrialCompartmentsProteinimportintomitochondriaProtein

3、TransportintoInnerMembraneandIntermembraneSpaceRequiresTwoSignalSequences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。Importofrubiscosm

4、all(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-TerminalTargetingSequencesPTS1PTS21.4ProteinsorttonucleusThenuclearporecomplex0.1umSideviewofnuclearpore1.4.1Nuclearproteintransportmechanism◆nuclearlocalizatio

5、nsignals,NLS◆nuclearexportsignals,NES◆importin◆exportinMechanismofproteinimportProteinsselectedforimportintonucleushaveanuclearlocalizationsignal(NLS)e.g.-Pro-Pro-Lys-Lys-Lys-Arg-NLSisrecognizedbycytosolicnuclearimportreceptorswhichbindtonuclearporefibrilsextendingintocytosolPore

6、opensandproteinplusimportreceptorenternucleus.Importreceptorexportedforre-useNuclearlocalizationsignalsNuclearlocalisationsignal(NLS)NuclearlocalizationsignalsNucleoplasminlabelandinjectionNucleoplasminlocationeffectMechanismoftransportthroughnuclearporesNLSneednotcutaftertranspo

7、rtNuclearimportProteintransportbynucleusporecomplexTransportisselectiveRestricttransportparticleRequireenergyexpendituresaturateddynamicTransportisdoubledirectionImportandexport1.4.2MechanismofexportfromnucleusMostoftrafficmovingoutofnucleusconsistsofdifferenttypesofRNAmoleculesR

8、NAmovesthroughnuclearporeascomplexofribo