Glycoprotein hormone subunit alpha 2 (GPHA2)

Glycoprotein hormone subunit alpha 2 is a cystine knot–containing protein encoded by the GPHA2 gene. In humans, it pairs with the GPHB5 subunit to form a heterodimeric glycoprotein hormone ("thyrostimulin") capable of binding and activating the thyroid-stimulating hormone receptor (TSHR), resulting in increased cAMP within thyroid cells and promoting thyroid hormone–related effects[2][3][1]. GPHA2's structure and role are homologous to the classic alpha subunits of pituitary glycoprotein hormones. However, as a single subunit, GPHA2 has no independent hormone activity; its function is realized only in the context of the heterodimeric hormone complex[1][2][3]. Diseases associated with GPHA2 mutations include Salt and Pepper syndrome and Norrie disease, although these links are rare and indirect[2]. GPHA2 itself is not a direct pharmacological target; rather, the thyrostimulin heterodimer and its receptor, TSHR, may be considered relevant to therapeutic and pathophysiological contexts[2][1].

Other names

GPA2Glycoprotein hormone alpha-2