[Steroid hormone receptors]

Steroid receptors belong to a superfamily of hydrosoluble nuclear proteins which regulate transcription of a number of genes. In the absence of hormone, they are bound to proteins which maintain the receptors in an inactive state but prepared for binding with the hormone. In the presence of the hormone, the receptor is activated, which is reflected by modification of its physico-chemical constants and dissociation of associated proteins. This hormone-receptor complex forms a homodimer and binds to DNA at the regulatory regions of the genes involved, which is termed "hormone response element". The receptors are constituted of 5 to 6 domains, each responsible for one or several functions. The hormone binding domain (region E) and DNA binding domain (region C) are the most highly conserved. Progress in the comprehension of the mechanism of action of these receptors has led to the development of antihormones which are important in the treatment of hormone-dependent cancer. With progress in molecular biology, it is now possible to detect mutants of the receptors or their absence in syndromes involving hormonal resistance.