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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
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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
Where? • 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
Zinc Finger II March 2007 Molecule of the Month by David Goodselldoi: 10.2210/rcsb_pdb/mom_2007_3
http://www.uic.edu/classes/bios/bios100/mike/spring2003/leucinezipper.jpghttp://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