Oestrogen receptors - an overview

The oestrogen receptor (ER) is a ligand-activated transcription factor that mediates the effects of the steroid hormone 17beta-oestradiol in both males and females. Since the isolation and cloning of ER, the prevailing opinion has been that only one such receptor exists. The finding of a second subtype of ER (ERbeta) has caused considerable excitement and has forced endocrinologists to re-evaluate many aspects of the actions of oestrogens. In this article, we will try to summarize the current knowledge about the two oestrogen receptor subtypes, with the emphasis on oestrogen receptor beta (ERbeta), and to comment on the observations in mice lacking either receptor or the hormone itself.