Diabetes-Associated Mutations in Insulin Identify Invariant Receptor Contacts
- Bin Xu1,
- Shi-Quan Hu2,
- Ying-Chi Chu2,
- Shuhua Wang2,
- Run-ying Wang2,
- Satoe H. Nakagawa3,
- Panayotis G. Katsoyannis2 and
- Michael A. Weiss1
- 1Department of Biochemistry, Case Western Reserve School of Medicine, Cleveland, Ohio
- 2Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York University, New York, New York
- 3Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois
- Address correspondence and reprint requests to Michael A. Weiss, Case Western Reserve University, Department of Biochemistry, 10900 Euclid Ave., SOM Room W427, Cleveland, OH 44106-4935. E-mail: michael.weiss{at}case.edu
Abstract
Mutations in human insulin cause an autosomal-dominant syndrome of diabetes and fasting hyperinsulinemia. We demonstrate by residue-specific photo cross-linking that diabetes-associated mutations occur at receptor-binding sites. The studies use para-azido-phenylalanine, introduced at five sites by total protein synthesis. Because two such sites (ValA3 and PheB24) are largely buried in crystal structures of the free hormone, their participation in receptor binding is likely to require a conformational change to expose a hidden functional surface. Our results demonstrate that this surface spans both chains of the insulin molecule and includes sites of rare human mutations that cause diabetes.
- DTT, dithiothreitol
- FnIII1, second fibronectin-homology domain
- ID, insert domain
- Pap, para-azido-phenylalanine
- Phe, phenylalanine
Footnotes
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- Accepted February 25, 2004.
- Received December 11, 2003.
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