《蛋白质分选》.ppt

Chapter 7 Protein sorting II-free-ribosome system 1 1整理整理pptpptsecretory pathway 2 2整理整理pptppt1.1 Synthesis and Targeting of Mitochondrialn n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。3 3整理整理pptppt 线粒体前体蛋白质在在运输以前，以未折叠的形线粒体前体蛋白质在在运输以前，以未折叠的形式存在，式存在，N N端有一段信号序列称为导肽或引肽，完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（成转运后被信号肽酶（signal peptidasesignal peptidase）切除，）切除，就成为成熟蛋白，这种现象就叫做后转译就成为成熟蛋白，这种现象就叫做后转译（posttranslationposttranslation）。）。信号肽的特点是：信号肽的特点是：多位于肽链的多位于肽链的N N端，由大约端，由大约2020个氨基酸构成；个氨基酸构成；形成一个两性形成一个两性 螺旋，带正电荷的氨基酸残基和不螺旋，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；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。对所牵引的蛋白质没有特异性要求。4 4整理整理pptpptMatrixOuter membraneIntermembrane spaceCross section of mitochondrionInner membrane5 5整理整理pptpptMitochondrial Proteins That Are Synthesized in the CytosolMitochondrial Proteins That Are Synthesized in the Cytosol6 6整理整理pptpptProteins Are Targeted to Sub-mitochondrial Proteins Are Targeted to Sub-mitochondrial CompartmentsCompartments7 7整理整理pptppt Protein import into mitochondria8 8整理整理pptpptProtein Transport into Inner Membrane and Intermembrane Space Requires Two Signal Sequences9 9整理整理pptppt线粒体转运与叶绿体非常相似线粒体转运与叶绿体非常相似1010整理整理pptppt1.2 Sort to Chloroplast Compartment1111整理整理pptppt叶绿体蛋白转运运输机理与线粒体的相似。如：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；都发生后转译；每一种膜上有特定的转位因子；每一种膜上有特定的转位因子；具有接触点（具有接触点（contact sitecontact site）；）；需要能量，同样利用需要能量，同样利用ATPATP和质子动力势；和质子动力势；前体蛋白前体蛋白N N端有信号序列，使用后被信号肽酶切端有信号序列，使用后被信号肽酶切除。除。但两者的蛋白质转运体系中除了某些但两者的蛋白质转运体系中除了某些hsphsp分子相分子相同外，转位因子复合体是不同的。同外，转位因子复合体是不同的。1212整理整理pptpptImport of rubisco small(S)subunits into the chloroplast stroma 转运肽1313整理整理pptppt内囊体膜蛋白转运需要两段信号内囊体膜蛋白转运需要两段信号1414整理整理pptppt1.3 Synthesis and Targeting of Peroxisome Proteins n n核基因合成，后转运方式运输核基因合成，后转运方式运输1515整理整理pptpptC-and N-Terminal Targeting SequencesPTS1PTS21616整理整理pptppt1.4 Protein sort to nucleus1717整理整理pptpptThe nuclear pore complex1818整理整理pptppt0.1um Side view of nuclear pore1919整理整理pptppt1.4.1Nuclear protein transport mechanismtransport mechanism nuclear localization signals,NLSnuclear export signals,NESimportinexportin 2020整理整理pptpptMechanism of protein importProteins selected for import into nucleus have a nuclear localization signal(NLS)e.g.-Pro-Pro-Lys-Lys-Lys-Arg-NLS is recognized by cytosolic nuclear import receptors which bind to nuclear pore fibrils extending into cytosolPore opens and protein plus import receptor enter nucleus.Import receptor exported for re-use2121整理整理pptpptNuclear localization signals 2222整理整理pptpptNuclear localisation signal(NLS)2323整理整理pptpptNuclear localization signals 2424整理整理pptpptN Nu uc cl le eo op pl la as smmi in n l la ab be el l a an nd d i in nj je ec ct ti io on n 2525整理整理pptpptNucleoplasmin location effect 2626整理整理pptpptMechanism of transport through nuclear poresNLS need not cut after transport 2727整理整理pptpptNuclear importNuclear import2828整理整理pptpptn nProtein transport by nucleus pore complexn nTransport is selective Restrict transport particle Require energy expenditure saturated dynamic n nTransport is double direction Import and export 2929整理整理pptppt1.4.2 Mechanism of export from nucleusMost of traffic moving out of nucleus consists of different types of RNA moleculesRNA moves through nuclear pore as complex of ribonucleoprotein(RNP):核糖核蛋白颗粒核糖核蛋白颗粒Protein component of RNP contains a nuclear export signal(NES)that is recognised by export proteinsmRNA is bound by hnRNP only after fully spliced so only mature RNA is exported3030整理整理pptpptnuclear RNA and protein export mRNA export 核内不均一核糖核蛋白核内不均一核糖核蛋白(heterogeneous ribonucleoprotein,hnRNP)信使信使RNP(messenger RNP,mRNP)mRNA的输出的输出nuclear proteinsnRNA export 3131整理整理pptpptsnRNA export snRNA export 3232整理整理pptpptNuclear export3333整理整理pptpptProtein importMaterial export3434整理整理pptppt