[Enhancers, DNA loops and stable complexes: a mechanism of transcription activation]

A recurrent theme in molecular biology is that of "action at a distance" along DNA. We consider various mechanisms of action of transcriptional enhancers as a well-characterised example of interaction between widely separated DNA-bound proteins. The role of promoter- and enhancer-binding proteins in the formation of a stable promoter complex, and the mechanisms of interaction between multiple activatory DNA sequences is also discussed.