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islet amyloid polypeptide, also called amylin, which is tied in with diabetes.
Amylin is a hormone that may moderate glucose metabolism. It is normally secreted along with insulin by pancreatic islet beta-cells. But deposits formed from fibrils of this amyloid peptide can be found in the islet cells of patients with type 2 diabetes. As with the other types of amyloid proteins, however, the researchers who support the membrane-hole hypothesis believe that these deposits aren't the pathogenic entities that impair and kill off the pancreatic cells. Oligomeric protofibrils formed by amylin can take on a conformation rich in -beta pleated sheet content, a structure that helps them insert themselves into cell membranes and form pores. He believes that the pores allow calcium to build up in the pancreatic cells, causing them to deteriorate and then die. Because these cells are responsible for secreting insulin, their death eventually leads to diabetes, the researchers propose.
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