Human Thyroid-Stimulating Hormone Receptor (TSHR) Protein

Background

TSHR is a G protein-coupled receptor activated by thyroid-stimulating hormone (TSH), a pituitary hormone that regulates thyroid gland growth and function. TSHR is primarily expressed on thyroid follicular cells, where its activation stimulates the production and release of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). TSHR signaling occurs via Gs proteins, leading to activation of adenylyl cyclase, increased cAMP levels, and stimulation of thyroid hormone synthesis, iodide uptake, and cell proliferation. TSHR plays a critical role in maintaining metabolic homeostasis, thermoregulation, and growth. Dysregulation of TSHR signaling is associated with thyroid disorders, such as Graves' disease (autoimmune hyperthyroidism), where TSHR autoantibodies lead to excessive hormone production, and hypothyroidism caused by receptor mutations. TSHR is also a target in thyroid cancers, where its overactivation promotes tumor growth. TSHR agonists and antagonists are being explored for therapeutic applications in thyroid dysfunction and thyroid-related cancers. TSHR is central to thyroid hormone regulation and overall metabolic balance.