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Amylin, or Islet Amyloid Polypeptide (IAPP), is a 37-residue peptide hormone.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3375 )〕 It is cosecreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1. Amylin plays a role in glycemic regulation by slowing gastric emptying and promoting satiety, thereby preventing post-prandial spikes in blood glucose levels. IAPP is processed from an 89-residue coding sequence. Proislet Amyloid Polypeptide (proIAPP,Proamylin, Proislet Protein) is produced in the pancreatic beta cells (β-cells) as a 67 amino acid, 7404 Dalton pro-peptide and undergoes post-translational modifications including protease cleavage to produce amylin. == Synthesis == ProIAPP consists of 67 amino acids, which follow a 22 amino acid signal peptide which is rapidly cleaved after translation of the 89 amino acid coding sequence. The human sequence (from N-terminus to C-terminus) is: (MGILKLQVFLIVLSVALNHLKA) TPIESHQVEKR^ KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTYG^ KR^ NAVEVLKREPLNYLPL.〔〔(【引用サイトリンク】title=islet amyloid polypeptide precursor (sapiens ) ) (the current NCBI RefSeq)〕 Once released from the signal peptide, it undergoes additional proteolysis and posttranslational modification ''(indicated by ^)''. 11 amino acids are removed from the N-terminus by the enzyme proprotein convertase 2 (PC2) while 16 are removed from the C-terminus of the proIAPP molecule by proprotein convertase 1/3 (PC1/3). At the C-terminus Carboxypeptidase E then removes the terminal lysine and arginine residues. The terminal glycine amino acid that results from this cleavage allows the enzyme peptidylglycine alpha-amidating monooxygenase (PAM) to add an amine group. Finally, a disulfide bond is formed between cysteine residues numbers 2 and 7. After this the transformation from the precursor protein proIAPP to the biologically active IAPP is complete (IAPP sequence: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY).〔 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「amylin」の詳細全文を読む スポンサード リンク
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