Expression and Activation of Gonadotropin Receptors

Abstract

Among the many hormones that are produced by the anterior pituitary gland, luteinizing hormone (LH, lutropin), follicle-stimulating hormone (FSH, follitropin), and thyroidstimulating hormone (TSH, thyrotropin) form the separate family of so-called glycoprotein hormones (reviewed by Oharib el al., 1990). These hormones consist of two glycosylated subunits, a and p, which are associated through non-covalent interactions. The a-subunit is identical for all glycoprotein hormones, whereas the p-subunit is hormone specific. The gonadotropins, LH and FSH, are the key regulators of testis and ovary function, and are synthesized in cells called the gonadotrophs of the pituitary gland. TSH, which regulates thyroid function, is produced in the thyrotrophs. In primates and horses, a fourth glycoprotein hormone exists, chorionic gonadotropin (CO), which is synthesized in the placenta during pregnancy, and is structurally and functionally related to LH (Oharib el al., 1990)