| Popis: |
Following the isolation and the identification of steroid hormones in the first half of this century, their mechanism(s) of action have been under investigation. The development of radiolabelled ligands allowed the identification of specific binding proteins, present intracellularly, that were translocated to the nucleus after binding with the steroid. The location of the steroid-protein complex suggested a link between this binding phenomenom and transcriptional activity as explanation of the physiological activity [1]. Further studies indeed demonstrated that steroid hormones exerted their biological activity after binding to these high-affinity binding proteins, named receptors, and that this binding induced an allosteric change in the receptor-protein that enabled the steroid-receptor complex to bind to high-affinity binding sites on the chromatin and to modulate transcriptional activity. It became established that steroid hormones act at the level of nuclear DNA and that they are involved in regulation of specific gene expression. |
