Targets of activated steroid hormone receptors: basal transcription factors and receptor interacting proteins.

Steroid hormone receptors constitute a family of inducible transcription factors that mediate the multi-fold effects of steroids on development, reproduction, proliferation, and cellular homeostasis. Activation through the binding of the cognate hormone enables the receptors to bind with high affinity to specific response elements in the promoters of target genes, resulting in stimulation or repression of transcription. While protein-protein interactions were early postulated to play an important role in the mechanism through which steroid hormone receptors exert their effects on transcription initiation, recent research has revealed a number of potential targets within the basal transcription machinery. Moreover, aided by the development of protein-protein interaction screening techniques, a rapidly increasing number of factors has been identified which associate with hormonally activated receptors and may be involved in the transactivation process. This review summarizes the basal transcription factors and cofactors which are targeted by steroid hormone receptors, describes their structure and properties, and discusses possible mechanisms.