The activation of transcription is a fundamental means of gene regulation. In eukaryotes a key component involved in transcriptional activation is the transcriptional activator. The activator functions by virtue of two, often separable, domains. The DNA binding domain is necessary for the activator to bind to specific DNA sequences found near the gene(s) which it regulates. The other domain, the activation domain, mediates the stimulation of transcription of that nearby gene (Hope and Struhl 1986). The mechanism by which these activation domains influence the rate of transcription has been the focus of much research over the last decade.