section m n transcription and regulation in eu

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1、TranscriptioninEukaryotesTranscriptioninEukaryotesThethreeRNAPolymerases:characterizationandfunctionRNAPolⅡgenes:promotersandenhancersEukaryoticRNApolymeraseactivitySimilaritiestothatinprokaryoticcells1.Don’trequireaprimer2.SynthesizeRNAina5’to3’direction.3.RNAcomplementarytotheantisensetemplatestr

2、and.Differences:1.Thereare3RNApolymerasesinEukaryotic2.RequiremoreaccessoryfactorsforbindingpromoterDNA&initiatingtranscription.3.TheC-terminusofRNAPolIIlargestsubunitcontainsastretchofheptapeptide(七聚体)repeats,namedascarboxylterminaldomain(CTD，羧基末端结构域)Aminoacidsequence:Tyr-Ser-Pro-Thr-Ser-Pro-Ser.R

3、epeated26x(yeast)&52xinmouse,whichInvolvedinpolymerasephosphorylation（磷酸化)duringelongation.Thebasicmechanismofeukaryotictranscriptionissimilartothatinprokaryotes.Muchmoreproteinsareassociatedwiththeeukaryotictranscriptionmachinery,resultinginmuchmorecomplicatedtranscription.BriefSummaryThethreeRNAP

4、olymerases:characterizationandfunctionThreeeukaryoticpolymerasestranscribedifferentsetsofgenes(Separationbydifferentsensitivitiesto-amanitin鹅膏菌素，amushroomtoxin真菌毒素）Inaddition,eukaryoticcellscontainadditionalRNAPolsinmitochondriaandchloraplasts.TypeLocationTranscriptionproductsSensitivityto-amanit

5、inRNAPolINucleoli（核仁）MostrRNAsgeneInsensitiveRNAPolⅡNucleoplasm（核质）Allprotein-codinggenesandsomesnRNAgenesVerysensitiveRNAPolⅢNucleoplasm（核质）tRNAs,5srRNA,U6snRNAandothersmallRNAsModeratelysensitiveThreeeukaryoticpolymerasesRNAPolIIgenes:promotersRNAPolIIRegulatoryelementsPromotersUpstreamregulatory

6、elementsRNAPolIIOverviewLocatedinnucleoplasm（核质）CatalyzingthesynthesisofthemRNAprecursorsforallprotein-codinggenes.RNAPolⅡ-transcribedpre-mRNAsareprocessedthroughCapaddition,poly(A)tailadditionandsplicing.PromotersMostpromotershaveasequencecalledtheTATAboxaround25-35bpupstreamfromthestartsiteoftran

7、scription.TATAboxisaA/T-richseptamer:7bpconsensussequenceconsistsentirelyofA:Tbasepairs(attwopositionstheorientationisvariable),andinonlyaminorityofactualcasesisaG:Cpairpresent.ActsinasimilarwaytoanE.colipr