An antidiabetic peptide secreted from pancreatic β-cells that forms amyloid fibrils; binds to amylin receptors (IC50s = 2 and 0.2 nM, respectively); forms fibrils that are organized in a cross-β arrangement of β-strands similar to Aβ40 and Aβ42; decreases the viability of primary pancreatic islet cell cultures by 60% (60 μM); inhibits electrically-stimulated contractions of guinea pig vas deferens (EC50 = 213 nM)