|
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) (). == Synthesis == TRH is produced by the hypothalamus 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). Following secretion, TRH travels across the median eminence to the anterior pituitary gland via the hypophyseal portal system where it stimulates the release of thyroid-stimulating hormone from cells called thyrotropes. TRH can also be detected in other areas of the body including the gastrointestinal system and pancreatic islets, as well as in the brain. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thyrotropin-releasing hormone」の詳細全文を読む スポンサード リンク
|