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Published byBrenda Patterson Modified over 9 years ago
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TATA box Promoter-proximal elements Effects of mutations in promoter element sequences on transcription
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Assembly of Transcription Initiation Complex Requires 7 basal transcription factors (TFs) + RNA Pol II TFIID = TBP + >8 TBP-Associated Factors (TAFs) TBP = TATA Binding Protein TFIIA added Remainder of basal TFs bind along with RNA Pol II TFIIB added Complete Transcription Initiation Complex
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Distance-independent elements Can be located at variable distances upstream from promoter. Can be located downstream of a gene or within introns. Can work in either orientation. Contain binding sites for TFs that regulate transcription.
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TFs that bind to enhancers &/or silencers regulate txn by helping or hindering assembly of transcription initiation complex.
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Regulation of transcription by steroid hormone receptors
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Functional Domains of Activators 1. DNA Binding Domain: Part of TF that binds to DNA. 2. Activation Domain: Part of TF that contacts other proteins (e.g., basal TFs)
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DNA Binding Motifs Motifs = stereotypical tertiary structures Helix-turn-helix motif Stabilization helix > 3 -helices separated by short turns (bends)
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Zinc-finger DNA binding motif C = Cysteine H = Histidine -helix: Contacts DNA in major groove -sheet
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