In accordance with the present invention, it has been discovered that various members of the steroid/thyroid superfamily of receptors can interact with the insect-derived ultraspiracle receptor, to form multimeric species. Accordingly, the interaction of at least one member of the steroid/thyroid superfamily of receptors with at least the dimerization domain of the ultraspiracle receptor modulates the ability of said member of the steroid/thyroid superfamily of receptors to transactivate transcription of genes maintained under hormone expression control in the presence of the cognate ligand for said member of the superfamily.