It is primarily found on the surface of the thyroid epithelial cells, but also found on adipose tissue and fibroblasts. The latter explains the reason of the myxedema finding during Graves disease. In addition, it has also been found to be expressed in the anterior pituitary gland, hypothalamus and kidneys. Its presence in the anterior pituitary gland may be involved in mediating the paracrine signaling feedback inhibition of thyrotropin along the hypothalamus-pituitary-thyroid axis.[7]
Function
Upon binding circulating TSH, a G-protein signal cascade activates adenylyl cyclase and intracellular levels of cAMP rise. cAMP activates all functional aspects of the thyroid cell, including iodine pumping; thyroglobulin synthesis, iodination, endocytosis, and proteolysis; thyroid peroxidase activity; and hormone release. TSHR is involved in regulating seasonal reproduction in vertebrates.[8]
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Murakami M, Mori M (Aug 1990). "Identification of immunogenic regions in human thyrotropin receptor for immunoglobulin G of patients with Graves' disease". Biochemical and Biophysical Research Communications. 171 (1): 512–8. doi:10.1016/0006-291X(90)91423-P. PMID1697467.
Heldin NE, Gustavsson B, Westermark K, Westermark B (Dec 1991). "A somatic point mutation in a putative ligand binding domain of the TSH receptor in a patient with autoimmune hyperthyroidism". The Journal of Clinical Endocrinology and Metabolism. 73 (6): 1374–6. doi:10.1210/jcem-73-6-1374. PMID1955520.
Libert F, Passage E, Lefort A, Vassart G, Mattei MG (1991). "Localization of human thyrotropin receptor gene to chromosome region 14q3 by in situ hybridization". Cytogenetics and Cell Genetics. 54 (1–2): 82–3. doi:10.1159/000132964. PMID2249482.
Misrahi M, Loosfelt H, Atger M, Sar S, Guiochon-Mantel A, Milgrom E (Jan 1990). "Cloning, sequencing and expression of human TSH receptor". Biochemical and Biophysical Research Communications. 166 (1): 394–403. doi:10.1016/0006-291X(90)91958-U. PMID2302212.
Nagayama Y, Kaufman KD, Seto P, Rapoport B (Dec 1989). "Molecular cloning, sequence and functional expression of the cDNA for the human thyrotropin receptor". Biochemical and Biophysical Research Communications. 165 (3): 1184–90. doi:10.1016/0006-291X(89)92727-7. PMID2558651.
Libert F, Lefort A, Gerard C, Parmentier M, Perret J, Ludgate M, Dumont JE, Vassart G (Dec 1989). "Cloning, sequencing and expression of the human thyrotropin (TSH) receptor: evidence for binding of autoantibodies". Biochemical and Biophysical Research Communications. 165 (3): 1250–5. doi:10.1016/0006-291X(89)92736-8. PMID2610690.
Cuddihy RM, Bryant WP, Bahn RS (Aug 1995). "Normal function in vivo of a homozygotic polymorphism in the human thyrotropin receptor". Thyroid. 5 (4): 255–7. doi:10.1089/thy.1995.5.255. PMID7488864.
"Glycoprotein Hormone Receptors: TSH". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2013-11-01. Retrieved 2007-10-25.