thyrotropin-releasing hormone receptor, member of the class A family of seven-transmembrane G protein-coupled receptors
TRH-R is a member of the class A rhodopsin-like G protein-coupled receptors, which binds the tripeptide thyrotropin releasing hormone. The TRH-R activates phosphoinositide metabolism through a pertussis-toxin-insensitive G-protein, the G(q)/G(11) class. TRH stimulates the synthesis and release of thyroid-stimulating hormone in the anterior pituitary. TRH is produced in many other tissues, especially within the nervous system, where it appears to act as a neurotransmitter/neuromodulator. It also stimulates the synthesis and release of prolactin. In the CNS, TRH stimulates a number of behavioral and pharmacological actions, including increased turnover of catecholamines in the nucleus accumbens. There are two thyrotropin-releasing hormone receptors in some mammals, thyrotropin-releasing hormone receptor 1 (TRH1) which has been found in a number of species including rat, mouse, and human and thyrotropin-releasing hormone receptor 2 (TRH2) which has, only been found in rodents. These TRH receptors are found in high levels in the anterior pituitary, and are also found in the retina and in certain areas of the brain.
Comment:based on the structures of some class A family members with bound ligands (peptides or chemicals), agonists, or antagonists
Comment:Small-molecule chemical ligands tend to bind deeper within the receptor core, compared to a peptide ligand neurotensin, which binds towards the extracellular surface of its receptor.
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