Transcript Transcription Factors

Transcription Factors
Extra Levels of Control
What?
• Transcription factors (TF)
– diffusible proteins
– act at numerous sites on many chromosomes
– Influence transcription by interacting with other
proteins or segments of DNA
• “Upstream” = being 5’ to the start site
– Negative numbers of bases
• “Downstream” = being 3’ to the start site
– Positive numbers of bases
Why?
• Finer control over transcription
– Recruits RNA Polymerase II
• Selective expression of specific genes
• Protection of promoter sequences
– Protection from denaturation & proteolysis
– TATA box, upstream promoter element (UPE),
Pribnow box, CpG islands, CAAT box, -10 to -35
• Adoption of specific 3D conformation of DNA
Upstream Promoter Element (UPE)
Transcription Inhibition
Where?
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Promoter & enhancer sequences on DNA
On transcriptional elements (TE) or enhansons
In the “open complex” of DNA
In the origin region of DNA
In the helix-loop-helix motif
In leucine zippers
In zinc fingers
TATA box binding
Zinc fingers
Zinc Finger II
March 2007 Molecule of the Month by David Goodsell
doi: 10.2210/rcsb_pdb/mom_2007_3
http://www.uic.edu/classes/bios/bios100/mike/spring2003/leucinezipper.jpg
Helix-loop-helix
n0b311a.blogspot.com
Helix-turn-helix
FEMS Microbiology Reviews 29 (2005) 231–262