Steroid hormone receptors are intracellular receptors (typically cytoplasmic ) that perform signal transduction for steroid hormones . Steroid hormone receptors are part of the nuclear receptor family that include a group of homologous structured receptors (type II receptors) that bind to non-steroid ligands such as thyroid hormones and vitamin A , as well as to vitamin D , and orphan receptors . All these receptors are transcription factors . They are usually located in the cytosol and move to the cell nucleus upon activation.
The ovarian hormones oestradiol and progesterone exert their actions on target cells predominantly through the binding and activation of the oestrogen receptor (ER) and progesterone receptor (PR), respectively. These receptors are members of the steroid/thyroid hormone superfamily of ligand-dependent transcription factors and bind to the control regions (promoters) of specific genes, where they recruit co-activators or co-repressors and the transcriptional machinery necessary to elicit gene expression. The ability of a nuclear receptor to modulate gene transcription is further dependent on its interaction with other transcription factors, which in turn can be regulated by either distinct or multiple cytoplasmic signalling pathways. This chapter summarises the extraordinary diversity of factors involved in determining the cellular response to a hormonal signal and emphasises the role of ER and PR in regulating ovarian and uterine functions.