LIFESCI 3 Chapter Notes - Chapter 15.3: Rna Polymerase Iii, Rna Polymerase Ii, Tata Box
Document Summary
Eukaryotic cells: 3 rna polymerases -- pol i, pol ii, and pol iii. Transcription factors: additional proteins required by eukaryotic polymerases to begin efficient transcription at promoter sequences. Binds to a specific promoter sequence and to a particular rna polymerase. Each type of rna polymerase only transcribes certain classes of genes. Pol i: binds to a single type of promoter that controls the expression of the pre-ribosomal. Rna (pre-rrna) transcript from which rrnas are derived. Pol ii: synthesizes mrnas, micrornas and some other noncoding rnas. Pol iii: recognizes promoter sequences for trnas, the 5s rrna, and some small regulatory rnas. Sequences usually in the transcribed region itself rather than upstream from the. Tata-binding protein (tbp): transcription factor used by all three rna polymerases. Binds to a tataaa sequence (tata box) near -30. Tbp-associated factors (tafs) recognize other promoter sequences and recruit tbp to the gene.
