MBB 222 Lecture Notes - Lecture 29: Tata-Binding Protein, Rna Polymerase Ii, Tata Box
20 Dec 2018
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Document Summary
In eukaryotes, mrna must be processed to form the final message/ transcript mrnas in eukaryotes are transcribed as pre-mrna or primary rna transcript (an unprocessed form of mrna) Eukaryotic cells are generally not organized into operons: one promoter/one gene (there are a few exceptions but polycistronic messages are not typical) Genes that encode proteins for steps within a given pathway are often spread widely across the genome. All mrnas are made by rna polymerase ii. Usually contains a tata box at ~-25 position with consensus sequence tataa/ta - is a core promoter element. Tata box is bound by the rnap ii tf, tfiid via its tata binding protein (tbp) - this is the first step in formation of the transcription complex. Initiator (inr) sequence at +1 (transcription start site) - dna is unwound here - many rnap. Ii promoters also contain a caat box (consensus gcccaatct) ~100-200 bp upstream of the transcription start site.
