The Steroid/Thyroid Hormone Receptor Family and Gene Regulation

The Second International CBT (Center for Biotechnology) Synposium was held in Stockholm November 4-5 1988 and had the title "The steroid/thyroid hoITIDne receptor family and gene regulation". This meeting contained contributions from most leading laboratories within the field of steroid/thyroid hOITIDne receptors and gave a very exciting perspective on the dynamic development of this i:ntx>rt. ant research field. Today all known steroid hoITIDne receptors have been cloned and sequenced and novel members of this supergene family are constantly being discovered. Sane of these new receptors remain to be characterized regarding the nature of their ligand. Access to probes for steroid receptors has enabled studies on mechanisms of regulation of receptor gene expression. Deletion and II'Altational analysis of steroid receptor cDNAs followed by expression in cells together with suitable reporter genes has yielded a detailed knowledge about the functional significance of the various domains the receptors are composed of. In certain cases, steroid resistance in patients have been shown to be due to point mutations in the corresponding steroid receptor genes resulting in non-functional receptors. The availability of receptor cDNAs also makes it possible to express receptors at high levels in procaryotic and eucaryotic cells. It is e. g. possible to express the DNA-binding domain of the glucocorticoid receptor in E. coli as a fusion protein with protein A which interacts specifically with DNA. Such studies are necessary for production of sufficient quantities of receptors to allow crystallization and X-ray crystallography for detailed structural information.