Figure 1.

Estrogen receptor (ER) chromatin binding is re-programed in a presence of progesterone-bound progesterone receptor (PR). (A) In the presence of estradiol, ER binds to estrogen-responsive elements (ERE) in a proximal region of the promoter, but in a presence of both hormones, estradiol and progesterone, hormone-bound receptors form a complex which binds to more distal progesterone-responsive elements (PRE), re-programing the transcription profile. (B) The progesterone/estradiol ratio changes depending on the phase of menstrual cycle, assuming the lowest numbers in post-menopausal women (approximate ratio based on a data from The Global Library of Women’s Medicine). The ratio may influence the transcription profile due to a regulation described above.