Lecture 18 Bio325 Fall 07

Lecture 18 Bio325 Fall 07 - Regulation of gene expression...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Regulation of gene expression can occur at any step from transcription through translation: binding of RNA polymerase to the promoter transcription initiation transcription elongation transcription termination RNA processing/RNA stability/nuclear export (mostly in eukaryotes) binding of mRNA to the ribosome translation post-translation modifications (mostly in eukaryotes) transcription translation • 3 RNA polymerases, many cofactors mRNA’s made only by RNA pol II Fig. 18.2
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Many basal transcription factors assist the binding of eukaryotic RNA polymerases to promoter regions. The key sequence-specific factor is the TATA-box-Binding Protein (TBP) which binds to the TATAA sequence; it recruits the other basal factors (~ 50 other proteins that comprise TFIID, plus TFIIA, TFIIB,TFIIE, TFIIF, TFIIH) and binds to many other TBP-associated Factors (TAF’s) Fig. 18.4 in eukaryotes, the distance between the TATA box and the transcriptional start site is variable, but usually about 30 nucleotides upstream of the start Transcription initiation in eukaryotic cells: • in addition to the promoter region, eukaryotic genes often contain specific sequence elements upstream (or occasionally downstream) of the coding region. These may be a few hundred base- pairs, or even millions of base-pairs away from the coding region. Sequence-specific transcription factors bind to these sites and contribute to transcription initiation at the promoter. The sequences bound by these proteins are called enhancer elements enhancers can work in either orientation relative to the promoter and can be downstream or upstream of the promoter region Fig. 18.5 Eukaryotic cis-acting elements: enhancers
Background image of page 2
3 www.cbs.dtu.dk/dave/roanoke/ genetics4.htm Activator proteins bind to sequences called enhancers; repressor proteins bind to sequences called silencers.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 9

Lecture 18 Bio325 Fall 07 - Regulation of gene expression...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online