In addition to promoters, enhancers also influence the expression of genes. Control of gene expression in eukaryotes involves many more factors than control in prokaryotes. This allows much finer control of gene expression. A“Simple” Eukaryotic Gene ...
activatorsoftranscriptioncanincrease promoteroccupancybyrecruitingRNApolymer- ase(Ptashne&Gann,1997).Aspartofadifferent controlstrategy,activatorscanalsochangetherate ofpost-promoterbindingstepssoastoincrease initiationrates.BacterialRNApolymerasesemploy sigmafactorsforpromoter-speci®cbinding.Escher- ichiacoliRNA...
(分枝位点):anA closetothe3’endoftheintron, whichisfollowedbya polypyrimidinetract(Pytract). (Lariat) 两次转酯化反应(transesterification): Step1:TheOHoftheconservedA atthebranchsiteattacksthe phosphorylgroupofthe conservedGinthe5’splicesite. Asaresult,the5’exonis releasedandthe5’-endofthe intron...
andactivators 21.17AnLCRmaycontroladomain 21.18Insulatorsblockenhanceractions 21.19Insulatorscanvaryinstrength 21.20Adomainhasseveraltypesofelements 21.21Geneexpressionisassociatedwithdemethylation 21.22CpGislandsareregulatorytargets Activationofgenestructure Initiationoftranscription Processingthetranscript Transporttocytoplasm ...
Prokaryote-like Activators –Bind to distant upstream regions called enhancers –Also bind to co-activator adaptors linked to core Repressors –Bind to silencers which interfere activator binding to enhancers. More realistic picture of transcription regulation ...
•Repressionisusuallyachievedbyaffectingchromatinstruc ture,buttherearerepressorsthatactbybindingtospecific promoters. fBIResponseElementsAreRecognizedbyActivators •Responseelementsmaybelocatedinpromotersor enhancers. •Eachresponseelementisrecognizedbyaspecificactivator. •Apromotermayhavemanyresponseelements,...
theyhaveleucinezip persthatcaninteracttoformhomodimersor heterodimers. TheothermajorcomponentofAPIisthe productofanothergenewithanoncogenic counterpart.Thec-fosgeneisthecellular homologtotheoncogenev-foscarriedbya murinesarcomavirus.Expressionofc-fosacti vatesgeneswhosepromotersorenhancerspos sessanAPI...
•activatorsandrepressors(激活蛋白和阻遏蛋白) •recruitmentandallostery,cooperativebinding(招 募,异构和协同结合) 2.Thegeneexpressionstepssubjectedtoregulation aresimilar,andtheinitiationoftranscriptionisthe mostpervasivelyregulatedstep. 4 Differenceinregulationbetweeneuk.andpro. ...
ChromatinTranscriptionLCR GlobingeneHistoneabstractChromatinstructureismodulatedduringtranscriptionalactivation.Thechangesincludetheassociationoftranscriptionalactivators,formationofhypersensitivesitesandcovalentmodificationsofhistones.Tounderstandtheorderofthevariouschangesaccompanyingtranscriptionalactivation,weanalyzedthemouse globin...
itsconformationchangeinducedbyproperactivators,suchasaminoacids,leadingtoaseriesofsignaltransductions tobraincells.Thestimulationofumamisensationbyactivatorsisgreatly(ingeneral,severalfolds)elevatedby suitableenhancers,suchasribonucleotides.Oneofthemostimportantfactorstoevaluatequalitiesofteasisthe ...