Analysis of steroid receptor domains with the aid of antihormones

1. The receptors for steroid hormones consist of well defined domains with overlapping functions. 2. Contrary to the classical view, it is now becoming increasingly evident that agonist binding regions of the ligand binding domain are not identical to those that bind steroid antagonists. 3. The DNA binding domain can be activated equally well in presence of both agonists and antagonists, again contradicting the classical view where only the physiologically active hormone was believed to induce such a change. 4. In some cases, a synthetic antagonist is a more specific ligand for the receptor than the natural hormone. 5. Synthetic antagonists are therefore important not only to alleviate disease in the human subject, they have also become an important tool to elucidate the mechanism of transactivation by steroid hormones.