Transcriptional regulators contain domains that either activate or repress
transcription. Indeed, many cellular transcriptional regulators contain bot
h activation and repression domains. Transcriptional regulators act at seve
ral stages in the transcription process, including assembly of the transcri
ption complex, initiation and elongation. In order to influence these proce
sses, the regulatory domains must interact with components of the transcrip
tion apparatus. This review will focus on our current understanding of the
nature of transcriptional regulatory domains and their targets in the trans
cription machinery.