Ligand binding domain of the glucocorticoid receptor, a member of the nuclear receptor superfamily
The ligand binding domain of the glucocorticoid receptor (GR): GR is a ligand-activated transcription factor belonging to the nuclear receptor superfamily. It binds with high affinity to cortisol and other glucocorticoids. GR is expressed in almost every cell in the body and regulates genes controlling a wide variety of processes including the development, metabolism, and immune response of the organism. In the absence of hormone, the glucocorticoid receptor (GR) is complexes with a variety of heat shock proteins in the cytosol. The binding of the glucocorticoids results in release of the heat shock proteins and transforms it to its active state. One mechanism of action of GR is by direct activation of gene transcription. The activated form of GR forms dimers, translocates into the nucleus, and binds to specific hormone responsive elements, activating gene transcription. GR can also function as a repressor of other gene transcription activators, such as NF-kappaB and AF-1 by directly binding to them, and bloc king the expression of their activated genes. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, GR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD). The LBD also functions for dimerization and chaperone protein association.