Abstract: Methods and genetic constructs are provided for detecting the binding of nuclear hormone receptors to a coactivator/corepressor. The methods employ enzyme fragment complementation using fragments of ?-galactosidase as the detection system. Cells are transformed to express the large fragment of ?-galactosidase fused to a member of the complex with NHR for initiation of transcription and have it localized in the nucleus and to express the small fragment of ?-galactosidase fused to the nuclear hormone receptor for binding to the member upon stimulation with a ligand.

Abstract: A method for determining ligand activation of receptors using cells expressing genetic constructs of a fusion protein of at least a binding domain of an auxiliary protein and a fragment of ?-galactosidase, a fusion protein of an endosome-associated protein and a complementary fragment of ?-galactosidase, and a wild-type receptor. The receptors are characterized by binding to the auxiliary protein-binding domain upon activation by an agonist and then endocytosing associated with an endosome to which the endosome-associated protein binds. Cells are incubated with a candidate ligand followed by lysis with a lysing medium comprising a substrate for the ?-galactosidase. The enzyme product is then detected as a measure of the activation of the receptor.

Abstract: A method for determining ligand activation of receptors using cells expressing genetic constructs of a fusion protein of at least a binding domain of an auxiliary protein and a fragment of ?-galactosidase, a fusion protein of an endosome-associated protein and a complementary fragment of ?-galactosidase, and a wild-type receptor. The receptors are characterized by binding to the auxiliary protein-binding domain upon activation by an agonist and then endocytosing associated with an endosome to which the endosome-associated protein binds. Cells are incubated with a candidate ligand followed by lysis with a lysing medium comprising a substrate for the ?-galactosidase. The enzyme product is then detected as a measure of the activation of the receptor.

Abstract: Methods and genetic constructs are provided for detecting the binding of nuclear hormone receptors to a coactivator/corepressor. The methods employ enzyme fragment complementation using fragments of ?-galactosidase as the detection system. Cells are transformed to express the large fragment of ?-galactosidase fused to a member of the complex with NHR for initiation of transcription and have it localized in the nucleus and to express the small fragment of ?-galactosidase fused to the nuclear hormone receptor for binding to the member upon stimulation with a ligand.