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1、5.TranscriptionIncluding5.1Transcriptioninprokaryotes5.2Regulationoftranscriptioninprokaryotes5.3Transcriptionineukaryotes5.4Regulationoftranscriptionineukaryotes5.5rRNAprocessandRNPs5.3Transcriptionineukaryotes5.3.1ThethreeRNApolymerases5.3.2RNAPolⅠgenes:theribosomalrepeat5.3.3RNAPolⅢg
2、enes:5sandtRNAtranscription5.3.4RNAPolⅡgenes:promotersandenhancers5.3.5GeneralTranscriptionFactorsandRNAPolⅡinitiation5.3.1ThethreeeukaryoticRNApolymerases:characterizationandfunction3RNAeukaryoticpolymerasestranscribedifferentsetsofgenes.Theiractivitiesaredistinguishedbytheirdifferents
3、ensitivitiestothefungaltoxinα-amanitin鵝膏藫堿.Ⅰ--mostrRNA----nucleoli(核仁)--insensitive;Ⅱ---mRNA;smallnuclearRNAs---nucleoplasm（核質）---verysensitive.Ⅲ---5srRNA,tRNA,U6snandotherRNAs---nucleoplasm---moderatelysensitive真核生物的RNA聚合酶種類 分布 合成的RNA類型 對α-鵝膏蕈堿的敏感性Ⅰ核仁rRNA不敏感Ⅱ核質hnRNA低濃度敏感Ⅲ核質tRNA，5sRNA
4、高濃度敏感Mt線粒體 線粒體RNAs不敏感RNApolymerasesubunitsAll3polymerasearelargeenzymescontaining12ormoresubunits.ThegeneencodingthetwolargestsubunitsofeachRNApolymerasehavehomologytoeachother.TheyhavehomologytoE.colicoreRNApolymerase.Thelargestsubunit---β';Thesecondlargestsubunit---β2commonsubunits
5、(Ⅰ,Ⅲ),1furthersubunit(Ⅱ)---σAtleast5subunitsarecommon,4to7areonlypresentinonetype.EukaryoticRNApolymeraseactivitiesLikebacterialRNApolymerase5'to3'AntisensetemplatestrandRequireATP,GTP,CTP,UTP;notrequireprimerUnlikebacterialenzymesRequirethepresenceofadditionalinitiationproteinsbeforeth
6、eyareabletopromoteandinitiatetranscription.TheCTDofRNApolⅡCTD(carboxyl-terminaldomain,羧基末端結構域)ThecarboxylendofRNApolⅡcontainsastretchofsevenaminoacid,Tyr(酪)-Ser(絲)-Pro(脯)-Thr(蘇)-Ser-Pro-Ser.52repeats-mouse,26repeats–yeast,thisrepeatsareessentialforviability(活性).TheCTDsequencemaybephosph
7、orylated(磷酸化).TheCTDhasbeenshowntobeanimportanttargetfordifferentactivationoftranscriptionelongation.5.3.2RNAPolⅠgenes:theribosomalrepeatRibosomalRNAgenesPre-rRNAtranscriptionunitscontainthreesequencesthatencodethe18S,5.8Sand28SrRNAs.Pre-rRNAtranscriptionunitsarearrangedinclust
