GnRHR is the receptor for type 1 gonadotropin-releasing hormone. GnRHR is a member of the seven-transmembrane, G protein-coupled receptor (GPCR) family. It is expressed on the surface of pituitary gonadotrope cells as well as lymphocytes, breast, ovary, and prostate. Following binding of gonadotropin-releasing hormone, GnRHR associates with G proteins that activate a phosphatidylinositol-calcium second messenger system. Activation of GnRHR ultimately causes the release of gonadotropic luteinizing hormone (LH) and follicle stimulating hormone (FSH). Defects in GnRHR are a cause of hypogonadotropic hypogonadism (HH).