Promoter site Proteins

Pig. 3. Representation of promoter sites on the pro-enkephalin gene. The numbers represent the distance in nucleotides from the pro-enkephalin initiation codon the arrow indicates the direction of transcription. The TATA promoter box occurs immediately before the pro-enkephalin initiation site the AP-2 site, which binds immediate-early gene products, is 70 nucleotides upstream, and the CRE site, which binds a regulatory protein involved in cAMP induction of mRNA synthesis, is 107 nucleotides upstream from the initiation codon. The expanded section shows that the CRE site actually consists of two elements, ENKCRE-1 and ENKCRE-2, which separately confer cAMP sensitivity to pro-enkephalin mRNA synthesis. 

To influence the activity of RNA polymerase, transcription factors bind to DNA at enhancer sites and/or promoter sites. Four different structures of these factors are known. They possess structures that allow specific binding to DNA. They are given names that indicate the key protein domains that encourage this binding, as follows ... 

At the DNA level, variability of the DNA elements specific for Stat proteins and accessibility of the promoter sites are further determining factors for specificity of signal transduction. 

Binding of protein transcription factors and RNA polymerase to promoter sites at the beginning of I a gene... 

Figure 13.1 Operon model for control of protein synthesis. The example chosen is the lactose (lac) operon. I, regulatory gene p, promoter site o, operator gene z, y, and a represent the structural genes for j8-galactosidase, permease, and transacetylase, respectively.

Based on their biochemical and genetic studies of the mechanism of transcription activation by 7-repressor, Hochschild and Dove realized that they could construct a bacterial activator system (Fig. 7.7C) [55, 56]. They simply placed the 7 operator upstream of a transcription start site. Protein-protein interactions could then be detected based on the ability of a 7-repressor-fusion protein to stabilize the interaction of RNA Pol with the promoter when the wild-type (wt) a-subunit of RNA Pol was replaced with an interacting a-subunit-fusion protein. In this system, the interaction of Gal4 with Galll, which has a Kn of 10 7M, increased lacZ transcription 45-fold. Recently, a... 

Eukaryotic genes encoding proteins have promoter sites with a TATAAA consensus sequence, called a TATA box or a Hogness box, centered at about -25 (Figure 5.27B). Many eukaryotic promoters also have a CAATbox with a GGNCT4TCT consensus sequence centered at about -75. Transcription of eukaryotic genes is further stimulated by... 

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