[Gonadotropin receptors]

The reproductive function of both the male and female is under the control of several pituitary hormones including lutropin (LH) and follitropin (FSH). These hormones are highly homologous glycoprotein dimers sharing a common subunit. Their polymorphism mainly resides in the microheterogeneity of their carbohydrate chains that is also responsible for the variations in biological activity. In the gonads, these hormones bind to specific receptors and regulate steroidogenesis and gametogenesis. LH receptors also bind the choriogonadotropin hormone and are located in Leydig cells in testis, interstitial and medulla cells in ovary. FSH receptors are present in Sertoli cells in the male while they control follicular maturation in the female. In both sexes, their activity is coupled to that of other receptors such as that of prolactin or one able to recognize GnRH. The purification of LH receptor has been successfully achieved in several animal species and showed a significant structural homology between the receptors of both sexes.