Experimental demonstration that hormone-binding domain of the glucocorticoid receptor (GR) mediates translocation to the nucleus in the presence of hormone. Cultured animal cells were transfected with expression vectors encoding the proteins diagrammed at the bottom. Immunofluorescence with a labeled antibody specific for beta-galactosidase was used to detect the expressed proteins in transfected cells. (a) When cells were transfected with beta-galactosidase alone, the expressed enzyme was localized to the cytoplasm in the presence and absence of the glucocorticoid hormone dexamethasone (Dex). (b) When a fusion protein consisting of beta-galactosidase and the entire 794-aa rat glucocorticoid receptor (GR) was expressed in the cultured cells, it was present in the cytoplasm in the absence of hormone but was transported to the nucleus in the presence of hormone. (c) A fusion protein composed of a 382-aa region of GR including the ligand-binding domain (light purple) and beta-galactosidase also exhibited hormone-dependent transport to the nucleus.
Note: beta-galactosidase is blue, activation domain is green, DNA-binding domain is orange, and ligand-binding domain is light purple.