The alpha chain of pituitary glycoprotein hormones (THYROTROPIN; FOLLICLE STIMULATING HORMONE; LUTEINIZING HORMONE) and the placental CHORIONIC GONADOTROPIN. Within a species, the alpha subunits of these four hormones are identical; the distinct functional characteristics of these glycoprotein hormones are determined by the unique beta subunits. Both subunits, the non-covalently bound heterodimers, are required for full biologic activity.

A small, unpaired gland situated in the SELLA TURCICA. It is connected to the HYPOTHALAMUS by a short stalk which is called the INFUNDIBULUM.

Hormones secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Structurally, they include polypeptide, protein, and glycoprotein molecules.