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TATA box Promoter-proximal elements Effects of mutations in promoter element sequences on transcription.

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Presentation on theme: "TATA box Promoter-proximal elements Effects of mutations in promoter element sequences on transcription."— Presentation transcript:

1 TATA box Promoter-proximal elements Effects of mutations in promoter element sequences on transcription

2 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

3 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.

4 TFs that bind to enhancers &/or silencers regulate txn by helping or hindering assembly of transcription initiation complex.

5 Regulation of transcription by steroid hormone receptors

6 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)

7 DNA Binding Motifs Motifs = stereotypical tertiary structures Helix-turn-helix motif Stabilization helix > 3  -helices separated by short turns (bends)

8 Zinc-finger DNA binding motif C = Cysteine H = Histidine  -helix: Contacts DNA in major groove  -sheet


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