INTERACTIONS BETWEEN THE RETINOID X RECEPTOR AND A CONSERVED REGION OF THE TATA-BINDING PROTEIN MEDIATE HORMONE-DEPENDENT TRANSACTIVATION

The retinoid X receptor (RXR) participates in a wide array of hormonal signaling pathways, either as a homodimer or as a heterodimer, with o ther members of the steroid and thyroid hormone receptor superfamily. In this report the ligand-dependent transactivation function of RXR ha s been characterized, and the ability of RXR to interact with componen ts of the basal transcription machinery has been examined. In vivo and in vitro experiments indicate the RXR ligand-binding domain makes a d irect, specific, and ligand-dependent contact with a highly conserved region of the TATA-binding protein, The ability of mutations that redu ce ligand-dependent transcription by RXR to disrupt the RXR-TATA-bindi ng protein interaction in vivo and in vitro suggests that RXR makes di rect contact with the basal transcription machinery to achieve activat ion.