Thyrotropin-releasing hormone (TRH) acts as a stimulator of hormone secretion from adenohypophyseal cells, and its signals are inactivated by TRH-degrading ectoenzyme.
The deduced 1,024-amino acid type II integral transmembrane protein is 96% identical to the rat protein. It has 12 putative C-terminal N-glycosylation sites, a potential tyrosine sulfation site (residue 380), a consensus sequence for zinc-dependent metallopeptidases, and a short N-terminal intracellular domain with a potential phosphorylation site. Northern blot analysis revealed expression of 7.5-, 7.0-, 6.0-, and 4.5-kb transcripts. Strongest expression was in brain, with weaker expression in heart, lung, liver, and skeletal muscle, and no expression in kidney and placenta.