(a)ReportertransgenesidentifyanenhancerGenetranscribed athigh levels in adulteyeonlyReporter constructs are atool foridentifyingPromoterAdult eye-Transcripts specificpromoters and enhancersinadulteyeenhanceronlyReportertransgenesPromoters andenhancersGFGFunderinvestigationarePromoterPromoterAdult eye-Basal level MHighlevelofMspecificGFPofGFPfused to the coding regionenhancertranscriptstranscriptsof reporter genes, such asinall cellsinadult eyeGFPproteinlacZorGFP.GFPGFPproteinGFPundetectable(b)TransgenicmouseexpressingGFPeye-specificallyFig. 16.3
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18-11 Reporter constructs Reporter constructs are a tool for identifying tool for identifying promoters and enhancers promoters and enhancers Promoters and enhancers Promoters and enhancers under investigation are under investigation are fused to the coding region fused to the coding region of reporter genes reporter genes, such as , such as lacZ or GFP. or GFP. Fig. 16.3
A1.TrappingElementSA ReporterGenePAReportern2.Geneconstructs canhelpidentifySDPromoterExonSAReporterGenepASAExonSDSAExonPApromoters andenhancers.3.TranscriptSDSAReporter GeneLAAAAAAAAA4.SplicedmRNAAAAAAAAAAAReporterGeneBE9.5E11.58e中...8D
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18-12 Reporter Reporter constructs can constructs can help identify help identify promoters promoters and enhancers enhancers
Trans-acting elements that control transcription initiationBasal factors:Proteins that bind to the promoter.MediatorTranscriptional activators and repressors: Proteins that bind tothe enhancers.trans-acting proteinsTranscriptionstartsiteEnhancerPromoterTranscribedregionTranscriptionfactors18-13Fig.16.4
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18-13 Trans-acting elements that control transcription initiation acting elements that control transcription initiation Basal factors Basal factors: Proteins that bind to the promoter. : Proteins that bind to the promoter. Mediator Mediator Transcriptional activators Transcriptional activators and repressors repressors: Proteins that bind to : Proteins that bind to the enhancers. the enhancers. Fig. 16.4
Basal factorsBasal factors bind tothe promoter.pol llTBP-TATA bOXbinding proteinTAFTAF-TBPTAFassociated factorsTATABOXRNA polymeraseIITBPbinds to basal factors.-3010Fig.16.518-14
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18-14 Basal factors Basal factors Basal factors Basal factors bind to bind to the promoter. the promoter. TBP – TATA box TATA boxbinding protein binding protein TAF – TBP associated factors associated factors RNA polymerase II RNA polymerase II binds to basal factors. binds to basal factors. Fig. 16.5
MediatorMediator:A protein complex that bridges theRNA pol Ilcomplex at the promoter and transcription factors attheenhancer.It is reguired for the transcription of some eukaryoticgenes.A complexthatcontainsmorethan2o proteins(a)ActivatorsrecruitRNApol llcomplextobasalpromoterPromoterTpollMediatorCDK8TAFTAFTBPMediator山1110TraActivatorinitIDRNAPolllEnhancerTBP主IIBIIAIFYIETATAFig. 16.6a18-15
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 18-15 Mediator Mediator Mediator Mediator: A protein complex that bridges the RNA : A protein complex that bridges the RNA pol II complex at the promoter and complex at the promoter and transcription factors at the transcription factors at the enhancer. It is required for the transcription of some eukaryoti enhancer. It is required for the transcription of some eukaryotic genes. A complex that contains more than 20 proteins. A complex that contains more than 20 proteins. Fig. 16.6a