1. 1 and 3 November, 2006 Chapter 17 Regulation in Eukaryotes

2. Overview Transcriptional initiation is the most common point to regulate gene expression. Eukaryotes must also integrate more signals, and must modify nucleosome positioning in order to activate transcription. Eukaryotic transcriptional activators are often modular, with DNA binding and activation domains. Eukaryotic transcriptional activators may bind as heterodimers. Classes of eukaryotic transcriptional activators include homeodomain, zinc finger, leucine zipper, and helix-loop-helix. Activators recruit the transcriptional machinery to the gene, interacting with mediator or TFII general factors. Activators may also promote chromatin modification. Insulators block activation by enhancers. Locus control regions open up chromatin to regulation by activators. Activators act synergistically. Eukaryotic transcription may be repressed by blocking or binding activators, interacting with mediator, or by modifying chromatin. Signal transduction pathways communicate with transcriptional regulators. DNA and histone modification can collaborate to effect regulation. Regulation may also occur at the levels of splicing, translation, and RNA stability.

3. Complex Eukaryotic Regulatory Regions

4. Modular Transcriptional Activators

5. The Two-hybrid System Again!

6. Homeodomain

7. Zinc Finger

8. Leucine Zipper

9. Helix-Loop-Helix

10. Potential Activator Contacts

11. Activator Bypass by LexA-Mediator Fusion

12. ChIP can identify binding sites.

13. Binding and Recruitment Assay

14. Gal4 recruits TFIIB

15. Activators may promote histone acetylation and / or chromatin remodeling.

16. Insulators block the effects of activators at enhancers.

17. Locus control regions make clusters of genes available for activation.

18. Possible Modes of Cooperative Binding of Activators

19. Synergistic Action of SWI5 and SBF in HO Expression

20. Signal integration at the INF-  gene

21. Combinatorial Control

22. Control of Cell-type Specific Genes in Yeast

23. Possible Modes of Action for Eukaryotic Repressors.

24. Signal transduction pathways regulate transcription factors.

25. Gal80 Regulates Gal4

26. Silencing through Histone Deacetylation

27. Silencing sometimes involves methylation and histone deacetylation.

28. Imprinting

29. Methylation patterns are heritable.

30. Transcriptional Regulation of Sxl

31. Regulated Alternative Splicing

32. Translational Control of GCN4

33. RNAi

34. Cooperative and Non-Cooperative Binding

36. Title