Nuclear receptors coordinate the activities of chromatin remodeling complexes and coactivators to facilitate initiation of transcription.

Recent advances in the field of in vitro chromatin assembly have led to in vitro transcription systems which reproduce in the test tube, in vivo characteristics of ligand-dependent transcriptional activation by nuclear receptors. Dissection of these systems has begun to provide us with information concerning the underlying molecular mechanisms. Through recruitment of coactivator proteins, nuclear receptors act first to remodel chromatin within the promoter region and then to recruit the transcriptional machinery to the promoter region in order to initiate transcription. Here we present a possible sequential mechanism for ligand-dependent transcriptional activation by nuclear receptors and discuss the in vitro and in vivo data that support this model.