protein synthesis initiation in prokaryotes

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1、ProteinSynthesisInitiationSecondaryarticleinProkaryotesArticleContents.IntroductionMarianneGrunberg-Manago,InstituteofPhysico-chemicalBiology,Paris,France.MessengerRNASelection–ShineandDalgarnoInteraction.StructureandFunctionofInitiationFactors(IFs)Theterm‘translationalinitiation

2、’referstothesequenceofeventsleadinguptothe.PathwayofInitiationComplexFormationformationofthefirstpeptidebond.Itisusuallytherate-limitingstepoftranslationandits.RoleofIF2-dependentGTPaseefficiencycanvarybyseveralordersofmagnitude.Itisthereforeamajordeterminantofthe.RibosomalBindin

3、gSitesintheInitiationComplexoverallexpressionlevelforageneandisatargetforavarietyoftranslationalcontrol.Acknowledgementsmechanisms.Introductionunderstandingoftranslationalinitiation(ShineandDalgarno,1974).NumerousexperimentssupporttheideaThepathwayfortheformationofthetranslationi

4、nitiationthatthissequenceisinvolvedininitiationsiteselection:(1)complexinvolvesnumerousindividualreactions,thelargethe3’terminalsequenceof16SrRNAishighlyconservedmajorityofwhichare‘noncovalent’innature.TheonlyandaccessibletomRNA;(2)oligonucleotidescomple-‘covalent’stepisthehydrol

5、ysisofguanosinetriphosphatementarytothisregionof16SrRNAinhibittranslation;(3)(GTP)toguanosinediphosphate(GDP)andPi.Akeyacomplexbetweentheribosome-bindingsiteofmRNAintermediateintheinitiationofproteinsynthesisisthe30Sanda3’terminalfragmentof16SrRNAwasisolatedfrominitiationcomplex,

6、consistingofthe30Sribosomalinitiationcomplexes(Hershey,1987).(seeMessengerRNAinsubunit,messengerRNA,theinitiatortransferRNAfMetprokaryotes.)(seeRibosomalRNA.)(seePeptidyltransferonthe(fMet-tRNA),GTPandthreeproteinfactors:IF1,IF2ribosome.)andIF3.IF3isinvolvedintheselectionoftheini

7、tiatorThebestdemonstration,however,wastheproductionoftRNA,butispossiblyreleasedfromthe30Ssubunitafterribosomescontaininganalteredanti-Shine–DalgarnoinitiatortRNAbinding.The30Scomplexthenassociatessequenceinthe16SrRNAinvivo.These‘specialized’withthe50Sribosomalsubunittoformthe70Si

8、nitiationribosomessynthesizeproteinonlyf