4. Estrogen Receptors Trigger Gene Activation
Estrogen receptors normally reside in the cell's nucleus, along with DNA molecules.
In the absence of estrogen molecules, these estrogen receptors are inactive and have no influence on DNA (which contains the cell's genes). But when an estrogen molecule enters a cell and passes into the nucleus, the estrogen binds to its receptor, thereby causing the shape of the receptor to change. This estrogen-receptor complex then binds to specific DNA sites, called estrogen response elements, which are located near genes that are controlled by estrogen.
After it has become attached to estrogen response elements in DNA, this estrogen-receptor complex binds to coactivator proteins and more nearby genes become active. The active genes produce molecules of messenger RNA, which guide the synthesis of specific proteins. These proteins can then influence cell behavior in different ways, depending on the cell type involved.