Functional dissection of the hormone and DNA binding activities of the glucocorticoid receptor.

We have identified two separate regions of the 795 amino acid rat glucocorticoid receptor that interact with hormonal ligands and DNA respectively. The functional regions were defined by direct assays of segments of the receptor coding sequence translated in vitro. Hormone affinity measurements suggested that residues near the receptor C-terminus are the primary determinants of ligand binding, whereas sequence-specific DNA binding activity resides between amino acids 440 and 546. DNA binding efficiency was stimulated only modestly by prior hormone binding. The receptor regions identified in these in vitro studies correspond to those that mediate ligand-dependent transcriptional enhancement in vivo.