Thyrotropin Receptor, a Glycoprotein Hormone Receptor, plays a central role in controlling thyroid cell metabolism. The TSH receptor can interact with both TSH and autoantibodies against the TSH receptor (thyroid-stimulating immunoglobulins, TSI). Mutations in the receptor are the cause for hyperthyroidism such as gestational hyperthyroidism (hypersensitivity to chorionic gonadotropin) and Grave's disease (autoimmune hyperthyroidism). Multiple isoforms of the thyrotropin receptor are produced by altervative splicing. The thyrotropin receptor has been reported in adipose, adrenal, brain, eye, heart, kidney, skin, thymus, and thyroid. ESTs have been isolated from brain, placenta, and thyroid libraries.