Hormonal Regulation of Pituitary Gonadotropin Gene Expression

Lutropin (LH) and follitropin (FSH) are two members of a family of structurally related polypeptide hormones, that also includes pituitary thyrotropin (TSH) and placental human chorionic gonadotropin (hCG). Each hormone of this family contains two non identical, non covalently linked subunits, α and β. The primary structure of the a subunits is identical among hormones within a species, whereas the primary structures of the β subunits differ greatly and confer to the hormones their specific biological activities (Pierce and Parsons, 1981). Although they are not identical, the β subunits show enough homology in their primary structures to suggest that they arose by duplications and mutations of a single ancestral gene (Fontaine and Burzawa-Gerard, 1977).