Estrogen Receptor (ER)
What is the Estrogen Receptor (ER)?
The estrogen receptor (ER) is a nuclear receptor that binds to steroid hormone estrogen (or estradiol) and regulates gene transcription. ER can be found throughout the body but is most associated with expression in the cells of female reproductive tissue and some cancer cells. ER is a cytosolic protein, that when activated translocates into the nucleus and binds to DNA to regulate the activity of its target genes. The estrogen receptor forms a homodimer and binds to specific sites in the DNA, strategically placed next to the genes that need to be regulated. Then, the receptor activates the transcriptional machinery and starts the production of messenger RNA. The two subtypes of the estrogen receptor, ERα and ERβ, have distinct tissue distributions and functions, and differ somewhat in their transcriptional activity and response to ligands.