Thyrotropin-releasing hormone

thyrotropin-releasing hormone
Structural formula of TRH
Identifiers
Symbol	TRH
Entrez	7200
HUGO	12298
OMIM	275120
RefSeq	NM_007117
UniProt	P20396
Other data
Locus	Chr. 3 q13.3-q21

Thyrotropin-releasing hormone (TRH), also called thyrotropin-releasing factor (TRF) or thyroliberin, is a releasing hormone, produced by the hypothalamus, that stimulates the release of thyrotropin (thyroid-stimulating hormone or TSH) and prolactin from the anterior pituitary. It is a tropic, tripeptidal hormone.

TRH has been used clinically for the treatment of spinocerebellar degeneration and disturbance of consciousness in humans. Its pharmaceutical form is called protirelin (INN) (/proʊˈtaɪrᵻlᵻn/).

TRH is produced by the globe in medial neurons of the paraventricular nucleus. At the beginning, it is synthesized as a 242-amino acid precursor polypeptide that contains 6 copies of the sequence -Gln-His-Pro-Gly-, flanked by Lys-Arg or Arg-Arg sequences.

To produce the mature form, a series of enzymes are required. First, a protease cleaves to the C-terminal side of the flanking Lys-Arg or Arg-Arg. Second, a carboxypeptidase removes the Lys/Arg residues leaving Gly as the C-terminal residue. Then, this Gly is converted into an amide residue by a series of enzymes collectively known as peptidylglycine-alpha-amidating monooxygenase. Concurrently with these processing steps, the N-terminal Gln (glutamine) is converted into pyroglutamate (a cyclic residue). These multiple steps produce 6 copies of the mature TRH molecule per precursor molecule for human TRH (5 for mouse TRH).