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Urotensin-II (U-II) is a peptide ligand, initially isolated from the neurosecretory system of the Goby fish (''Gillichthys mirabilis''). For many years it was thought that U-II does not exhibit significant effects in mammalian systems; a view quickly overturned when it was demonstrated that Goby U-II produces slow relaxation of mouse anococcygeus muscle, in addition to contraction of rat artery segments. In 1998, the cDNA encoding a U-II precursor was cloned in humans, unequivocally demonstrating its existence in mammalian species.The vasoconstriction it induces can cause or exacerbate hypertension, congestive heart failure, and coronary artery disease. In fish, U-II is secreted at the back part of the spinal cord, in a neurosecretory center called ''uroneurapophysa'', and is involved in the regulation of the renal and cardiovascular systems.〔L. Fishelson, Zoology, renewed and corrected ed. 1984, Hakibutz Hameuchad Pub. House, Israel 1984. Vol II, p.126 (Hebrew)〕 In mammals, it is involved in the regulation of the cardiovascular system. == U-II peptide == As with other peptide ligands, U-II is synthesised from a larger precursor molecule known as Prepro-urotensin-II. Two isoforms have been identified in man of lengths 124 and 139 residues. Cleavage of either of these precursors produces identical, eleven residue, mature U-II peptides. The cyclic, C-terminal hexapeptide sequence((-CYS *-TRY-LYS-TRP-PHE-CYS *-), ( *bridged CYS residues)), has been conserved through evolution from lamprey to human species, which diverged some 560 million years ago. The fact that such a strong evolutionary pressure has acted to conserve this sequence highlights its physiological importance. Indeed, this hexapeptide sequence confers biological activity. 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「Urotensin-II」の詳細全文を読む スポンサード リンク
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