细胞生物学蛋白分选-protein-sorting课件

Proteintargetingorproteinsorting,Roadmapofproteinsorting,Golgi,？,1972年，C.Milstein发现在骨髓瘤细胞中提取的免疫球蛋白分子的N端要比分泌到细胞外的免疫球蛋白分子N端多一段氨基酸序列。,一、TheSignalHypothesissiteofsynthesisdeterminedbyinformationcontainedinN-terminusofprotein(firstparttoemergefromribosome),信号假说,TheNobelPrizeinPhysiologyorMedicine1999,“Dr.GuenterBlobelatNewYorksRockefellerUniversitywontheNobelPrizeinmedicineMonday(October,1999)fordiscoveringhowproteinsfindtheirrightfulplacesincells.”,GnterBlobel,bornin1936,worksattheLaboratoryofCellBiology,TheRockefellerUniversity,NewYork,Signalhypothesis,Howdonewlysynthesizedproteinsfindtheircorrectdestinationswithinacell?andhowaretheyabletopassacrossthetightlysealedintracellularmembranes?,ERproteinhasN-terminalsignalsequence,cytosolicproteindoesnot.,SignalpeptiderequiredforimportintoER,Roleofsignalsequenceinproteinsorting,ERproteinhasN-terminalsignalsequence,cytosolicproteindoesnot.,Roleofsignalsequenceinproteinsorting,PuttingsignalsequenceontonormallycytosolicproteinresultsinitsimportintoER,i.e.,Signalpeptide,Consistsofshortstretchofaminoacids(15-25aminoacids),Nosequencehomology-butisstructuralhomology,notablyhydrophobicaminoacids,SignalsequencedirectsribosomestobindtoERmembranebeforeproteinfullysynthesised,Co-TranslationalTransportrequiresacomplex,SRP-signalrecognitionparticle-andaSRPreceptoronERmembrane,SRPandSRPReceptorEssentialforCo-TranslationalTransport,SRP,Thesignalrecognitionparticleinmammaliancellsismadefrom:Asinglesmall(7S)moleculeofRNASixdifferentmoleculesofprotein,TargetingtotheERmembrane,TheSRPreceptor,alsocalledthedockingprotein,onthesurfaceoftheERmembranesfacingthecytosol.SRPandSRPreceptorcanrecognizeandbindeachotheronERmembranes.,Signalhypothesis,核糖体上信号肽合成SRP识别信号肽，肽链合成暂停SRP与受体结合，核糖体与ER结合SRP返回胞质，肽链合成继续信号肽被切除核糖体分离，成熟蛋白落入ER腔,SRP受体,穿膜信号,全部穿膜,跨膜蛋白,StarttransfersequenceStoptransfersequence,穿膜信号,新生肽链上有起始穿膜信号和终止穿膜信号。起始信号即氨基端的信号肽。,信号肽的跨膜机制,信号肽在多肽链的内部。内信号肽可将核糖体引导到细胞膜，也作为插入信号启动多肽链的插入。内信号肽不切除,以螺旋的形式单次跨膜.,(Internalsignalpeptide),含内信号肽的单次跨膜机制,内信号肽可以两个不同的方向引导插入，取决于内信号肽两端的氨基酸段所带正电荷的多少。,内信号肽的多次跨膜机制,内部信号序列起始多肽转运和转移，当一终止序列进入转运通道，通道将两个序列都释入脂双层，两个序列均不被切除，整个多肽链作为穿膜两次的跨膜蛋白定位在膜中。多次穿膜蛋白质则有更多的起始和终止序列对，每一对都重复上述同样的过程。,胞质蛋白质合成,signal信号,posttranslocation,cotranslocation,信号序列signalsequence输入细胞核-Pro-Pro-Lys-Lys-Lys-Arg-Lys-Val-输出细胞核-Leu-Ala-Leu-Lys-Leu-Ala-Gly-Leu-Asp-Ile-输入线粒体+H3N-Met-Leu-Ser-Leu-Arg-Gln-Ser-Ile-Arg-Phe-Phe-Lys-Pro-Ala-Thr-Arg-Thr-Leu-Cys-Ser-Ser-Arg-Tyr-Leu-Leu-输入质体+H3N-Met-Val-Ala-Met-Ala-Met-Ala-Ser-Leu-Gln-Ser-Ser-Met-Ser-Ser-Leu-Ser-Leu-Ser-Ser-Asn-Ser-Phe-Leu-Gly-Gln-Pro-Leu-Ser-Pro-Ile-Thr-Leu-Ser-Pro-Phe-Leu-Gln-Gly-输入过氧化物酶体-Ser-Lys-Leu-COO-输入内质网+H3N-Met-Met-Ser-Phe-Val-Ser-Leu-Leu-Leu-Val-Gly-Ile-Leu-Phe-Trp-Ala-Thr-Glu-Ala-Glu-Gln-Leu-Thr-Lys-Cys-Glu-Val-Phe-Gln-返回内质网-Lys-Asp-Glu-Leu-COO-（KDEL）由质膜到内体Tyr-X-X-,二、分选的基本途径与类型,post-translationtranslocationCo-translationtranslocationTransmembranetransportVesiculartransportGatedtransport,分选方式,门控性转运,穿膜转运,膜泡转运,胞质蛋白质合成,Transmembranetransport,膜泡运输,细胞质基质中的蛋白质转运,vesiculartransport,分选方式,三、膜泡运输,1,2,3,4,5,7,6,vesiculartransport,vesiculartransport,三、vesiculartransport,衣被类型运输方向COPIGolgibodyERCOPIIERGolgibodyClathrinGolgibodyplasmamembraneGolgibodylysosomeplasmamembraneendosome,LumenalERproteinsaretakenupbythevesiclesandreleasedintothelumenoftheGolgi.Allofvesiclesarecoated(COP).,AssoonasGolgireceptorbindsretentionsignal,theretentionproteinsbudfromthecis-Golgiandthenformacoated(COP)vesicleselectivelyreturnedtotheER.,anterogradetransport,retrogradetransport,转运小泡对GC的定向,各类运输小泡之所以能够被准确地和靶膜融合，是因为运输小泡表面的标志蛋白能被靶膜上的受体识别，涉及两类关键蛋白：SNARE：介导运输小泡特异性停泊和融合Rab：使运输小泡靠近靶膜,v-SNARE：位于转运小泡膜上,t-SNARE：位于靶膜上,v-SNARE：位于转运小泡膜上,t-SNARE：位于靶膜上,Rab属于单体GTP酶：促进和调节运输小泡的停泊和融合，起分子开关作用；帮助运输小泡聚集和靠近靶膜。,Rab-GTP,Pi,Reviewemphasesforendomembranesystem,1.OutlinethefunctionsofsERandrER2.Outlinethesignalhypothesis.3.OutlinethecharacteristicsofN-linkedproteinglycosylation