Gene expression/regulation enhancers

Regulatory regions are transcriptional control sequences, which consist of promoters, response elements, enhancers and possibly silencers, located upstream of the start site of transcription. The overall effect on gene transcription is a sum of the contributions of these elements and the activities of proteins recruited to these sites. Promoters are located immediately upstream of the start site and initiate transcription. They often contain tissue- or cell-specific elements if the gene is not ubiquitously expressed. Enhancers are positive regulatory elements which function independently of orientation and distance from the genes they regulate. 

Phosphorylation of HSF substantially enhances the transcriptional activity of HS gene expression which may be up to 100-fold of basal levels after HSFl binds to the promoter element. Heat shock will increase the C-terminal-domain-kinase activity in cell extracts, and this action may enhance the activity of RNA polymerase II that is bound to HS genes (Legagneux et al., 1990). Whether this kinase activity also affects HSFl phosphorylation is not known, but increased HS gene expression appears to occur as long as HSFl is bound to the promoter region. The CTD kinase complex contains multiple proteins, and it is quite possible that one or more of these proteins is also regulated by stress. 

Libermann, T. A., Lenardo, M., and Baltimore, D. (1990). Involvement of a second lymphoid-specific enhancer element in the regulation of immunoglobulin heavy-chain gene expression. Mol. Cell. Biol. 10 3155-3162. 

---