A Two-Hybrid Protein Interaction System to Identify Factors That Interact with Retinoid and Vitamin D Receptors

Steroid hormone receptors activate and repress gene transcription through an integrated series of protein-protein interactions. One principle contact is the interaction of the nuclear receptors with one another to form both homodimeric and heterodimeric complexes that bind with high affinity to their cognate DNA-responsive elements. Following receptor-response element binding, the DNA-bound homodimers and heterodimers must ultimately communicate with the preinitiation complex to influence RNA polymerase II-mediated transcrrption. This communication process presumably involves additional proteinprotein contacis. Identifying these contacis, the proteins that are involved, and the precise nature of these interactions are central to our understanding of this fundamental mechanism.