MED23: Proteins and Enzymes

DRIPs are a distinct set of ligand-dependent proteins that interact with the vitamin D receptor (VDR). Together, these proteins constitute a new cofactor complex. DRIPs bind to several nuclear receptors to mediate ligand-dependent enhancement of transcription by VDR and the thyroid hormone receptor in cell-free transcription assays. The DRIPs are almost indistinguishable from components of another cofactor complex called ARC, which is recruited by other types of transcription activators to mediate transactivation on chromatin-assembled templates. The role of nuclear-receptor ligands may, in part, be to recruit such a cofactor complex to the receptor and, in doing so, to enhance transcription of target genes. In humans, interaction with Sur-2 is required for transcription to be activated by the activation domain of a transcription factor of the ETS-family in response to activated mitogen-activated protein (MAP) kinase.