Mechanism of action of the sex steroid hormones (first of three parts).

The mechanism of action of the sex steroid hormones is reviewed. Bi nding of steroid hormone (estrogen, progesterone, androgen) by target tissue, translocation of the hormone-receptor complex into the nucleus, hormone-receptor interactions with chromatin, and effects of the sex steroid hormones on chromatin structure are the main topics of discussio n. In general, after the steroid hormone is bound to a cytoplasmic receptor the transfer of the hormone-receptor complex into the target cell nucleus takes place. This is where the hormone exerts its influence on gene activity. Once the steroid-receptor complex moves into the nucleus it undergoes an interaction with the deoxyribonucleic acid-nucleoprotein complex of the cell nucleus that is often referred to as chromatin. The steroid hormone may exert its influence on gene function through this interaction. Current concepts of hormone action suggest that interaction of steroid hormones leads to increased ribonucleic acid synthesis and subsequently to protein synthesis.