Gene expression can be regulated at different levels

• Differential gene transcription

• Selective nuclear RNA processing

• Selective messenger RNA translation

• Differential protein modification

5.1 Nucleosome and chromatin structure

5.2 Nucleotide sequence of the human β-globin gene

5.4 Formation of the active eukaryotic transcription initiation complex (Part 1)

5.4 Formation of the active eukaryotic transcription initiation complex (Part 2)

5.5 Model of TAF stabilization of TBP

5.6 The genetic elements regulating tissue-specific transcription can be identified by fusing reporter genes to suspected enhancer regions of the genes expressed in particular cell types

5.7 Regulatory regions of the mouse Pax6 gene

Transcription factors

• Transcription factors are proteins that bind to enhancer or promoter regions and interact to activate or repress the transcription of a particular gene.

• Most transcription factors can bind to specific DNA sequences.

• 3 major domains:

- DNA-binding domain: recognizes a particular DNA sequence

- trans -activating domain: activates or suppresses the transcription of the gene whose promoter or enhancer it has bound.

- Protein-protein interaction domain: allows the transcription factor’s activity to be modulated by TAFs or other transcription factors.

5.9 Serial sections of the eye in 15.5-day mouse embryos demonstrate that MITF is required for the transcription of pigmention genes

5.10 TAFII250, a TAF that binds TBP, can function as a histone acetyltransferase

Numerous transcription factors operate by recruiting histone acetyltransferases.

5.18 Silencers