This family consists of several thyrotropin-releasing hormone (TRH) proteins. Thyrotropin-Releasing Hormone (TRH) is a tripeptide (pGlu-His-Pro-NH2) hormone that is primarily produced in the paraventricular nucleus of the hypothalamus and represents the most proximal member of the hypothalamic-pituitary-thyroid (HPT) axis. It plays an important role in maintaining the thyroid hormone (TH) homeostasis [].
TLC is a protein domain with at least 5 transmembrane α-helices. Lag1p and Lac1pare essential foracyl-CoA-dependent ceramide synthesis [], TRAM is a subunitof the translocon and the CLN8gene is mutated in Northern epilepsy syndrome. Proteins containing this domain may possessmultiple functions such aslipid trafficking, metabolism, or sensing. Trh homologues possess additionalhomeobox domains [].
Thyrotropin-releasing hormone, also known as thyroliberin (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 behavioural and pharmacological actions, including increased turnover of catecholamines in the nucleus accumbens []. TRH initiates all of these effects by interacting with receptors that belong to a class of G protein-coupled receptors, rhodopsin-type (GPCRA) [].There are two thyrotropin-releasing hormone receptors, thyrotropin-releasing hormone receptor (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 [, , ]. The receptors activate phosphoinositide metabolism through a pertussis-toxin-insensitive G-protein, probably of the Gq/G11 class [, ]. This entry represents the thyrotrophin-releasing hormone receptor.
Pyroglutamyl-peptidase II (also known as thyrotropin-releasing hormone-degrading ectoenzyme (TRH-DE); MEROPS identifier M01.008) is a member of the M1 family of Zn-dependent aminopeptidases and catalyses the degradation of TRH []. Pyroglutamyl-peptidase II is a transmembrane protein. The large extracellular domain contains the catalytically active site, which has nine cysteine residues that are highly conserved among species.
