Interactions of sex hormone-binding globulin with target cells

Sex hormone-binding globulin (SHBG) was initially described as a plasma protein synthesized in, and secreted by, the liver. It was discovered by its ability to bind certain androgens and estrogens and, for many years, was believed to serve as a transporter/reservoir for the steroids which it bound. Subsequently, it became clear that the cell membranes of selected tissues contained a receptor for SHBG (RSHBG). This review deals with what is known of that receptor – its anatomy, physiology and biochemistry.