Structural highlights
FunctionMALE_ECOLI Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.IAPP_HUMAN Selectively inhibits insulin-stimulated glucose utilization and glycogen deposition in muscle, while not affecting adipocyte glucose metabolism. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIslet Amyloid Polypeptide (IAPP or amylin) is a peptide hormone produced and stored in the beta-islet cells of the pancreas along with insulin. IAPP readily forms amyloid fibrils in vitro, and the deposition of fibrillar IAPP has been correlated with the pathology of type II diabetes. The mechanism of the conversion that IAPP undergoes from soluble to fibrillar forms has been unclear. By chaperoning IAPP through fusion to maltose binding protein, we find that IAPP can adopt a alpha-helical structure at residues 8-18 and 22-27 and that molecules of IAPP dimerize. Mutational analysis suggests that this dimerization is on the pathway to fibrillation. The structure suggests how IAPP may heterodimerize with insulin, which we confirmed by protein crosslinking. Taken together, these experiments suggest the helical dimerization of IAPP accelerates fibril formation and that insulin impedes fibrillation by blocking the IAPP dimerization interface. Atomic structures of IAPP (amylin) fusions suggest a mechanism for fibrillation and the role of insulin in the process.,Wiltzius JJ, Sievers SA, Sawaya MR, Eisenberg D Protein Sci. 2009 Apr 29. PMID:19475663[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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