Amyloid fibrils in human insulinoma and islets of Langerhans of the diabetic cat are derived from a neuropeptide-like protein also present in normal islet cells.
Amyloid deposits localized to the islets of Langerhans are typical of non-insulin-dependent human diabetes mellitus and of diabetes mellitus in adult cats. Amyloid deposits also commonly occur in insulin-producing pancreatic tumors. We have purified a major protein--insulinoma or islet amyloid polypeptide (IAPP)--from human and cat islet amyloid and from amyloid of a human insulinoma. IAPP from human insulinoma contained 37 amino acid residues and had a theoretical molecular mass of 3850 Da. The amino acid sequence is unique but has greater than 40% identity with the human calcitonin gene-related peptide. A partial amino acid sequence of cat islet IAPP corresponding to positions 1-27 of human insulinoma IAPP was identical to the human IAPP except for substitutions in three positions. An antiserum raised to a synthetic human insulinoma IAPP-(7-17) undecapeptide showed specific immunohistochemical reactivity with human and cat islet amyloid and with islet B cells. The significance of this pancreatic neuropeptide-like protein is unknown, but it is suggested that it may exert an important endocrine regulatory effect.
D007516:Adenoma, Islet Cell / Q000473:pathology*; D000595:Amino Acid Sequence; D000682:Amyloid / Q000302:isolation & purification*; D000818:Animals; D002371:Cat Diseases / Q000473:pathology*; D002415:Cats; D003920:Diabetes Mellitus / Q000473:pathology / Q000662:veterinary*; D003924:Diabetes Mellitus, Type 2 / Q000473:pathology*; D006801:Humans; D007118:Immunoassay; D007340:Insulinoma / Q000473:pathology*; D007515:Islets of Langerhans / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000473:pathology*; D013045:Species Specificity
D000682:Amyloid