Structure and function of nuclear hormone receptors.

Nuclear hormone receptors are a class of transcription factors whose activity depends on the binding of a ligand. The proteins are structurally and functionally related and include the receptors for steroid hormones, thyroid hormone and a number of vitamins, including the morphogen retinoic acid. The regions of the receptor responsible for ligand binding, nuclear localization, protein dimerisation, DNA binding and transcriptional transactivation have been identified and the functional domains are now being characterized. An aberrant form of the thyroid hormone receptor, v-erb A, is oncogenic in avian erythroid cells and androgens and oestrogens influence the growth of a number of common human cancers. Drugs that antagonise the action of these steroids are being developed and some of them are clinically useful.