glycoprotein hormone, alpha subunit MeSH:D015292 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. follicle stimulating hormone luteinizing hormone chorionic gonadotropin thyrotropin