Mapping of epitopes for autoantibodies to the type 1 diabetes autoantigen IA-2 by peptide phage display and molecular modeling: overlap of antibody and T cell determinants

Dromey, Jame A. and Weenink, Sarah M. and Peters, Gunther H. and Endl, Josef and Tighe, Patrick J. and Todd, Ian and Christie, Michael R. (2004) Mapping of epitopes for autoantibodies to the type 1 diabetes autoantigen IA-2 by peptide phage display and molecular modeling: overlap of antibody and T cell determinants. Journal of Immunology, 172 (7). pp. 4084-4090. ISSN 0022-1767

Full content URL: http://www.jimmunol.org/content/172/7/4084.full

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Mapping of epitopes for autoantibodies to the type 1 diabetes autoantigen IA-2 by peptide phage display and molecular modeling: overlap of antibody and T cell determinants

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Abstract

IA-2 is a major target of autoimmunity in type 1 diabetes. IA-2 responsive T cells recognize determinants within regions represented by amino acids 787-817 and 841-869 of the molecule. Epitopes for IA-2 autoantibodies are largely conformational and not well defined. In this study, we used peptide phage display and homology modeling to characterize the epitope of a monoclonal IA-2 Ab (96/3) from a human type 1 diabetic patient. This Ab competes for IA-2 binding with Abs from the majority of patients with type 1 diabetes and therefore binds a region close to common autoantibody epitopes. Alignment of peptides obtained after screening phage-displayed peptide libraries with purified 96/3 identified a consensus binding sequence of Asn-x-Glu-x-x-(aromatic)-x-x-Gly. The predicted surface on a three-dimensional homology model of the tyrosine phosphatase domain of IA-2 was analyzed for clusters of Asn, Glu, and aromatic residues and amino acids contributing to the epitope investigated using site-directed mutagenesis. Mutation of each of amino acids Asn858, Glu836, and Trp799 reduced 96/3 Ab binding by >45%. Mutations of these residues also inhibited binding of serum autoantibodies from IA-2 Ab-positive type 1 diabetic patients. This study identifies a region commonly recognized by autoantibodies in type 1 diabetes that overlaps with dominant T cell determinants.

Keywords:amino acid, asparagine, autoantigen, autoantigen ia 2, epitope, glutamic acid, monoclonal antibody, monoclonal antibody ia 2, peptide, protein tyrosine phosphatase, unclassified drug, amino acid sequence, antigen binding, article, autoimmunity, binding competition, binding site, consensus sequence, human, human cell, insulin dependent diabetes mellitus, molecular model, phage display, prediction and forecasting, priority journal, protein domain, sequence analysis, sequence homology, site directed mutagenesis, T lymphocyte, Amino Acid Sequence, Amino Acid Substitution, Antibodies, Monoclonal, Autoantibodies, Autoantigens, Bacteriophage M13, Binding Sites, Antibody, Clone Cells, Diabetes Mellitus, Type 1, Epitope Mapping, Epitopes, T-Lymphocyte, Humans, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Peptide Library, Protein Conformation
Subjects:C Biological Sciences > C550 Immunology
Divisions:College of Science > School of Life Sciences
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ID Code:18131
Deposited On:07 Aug 2015 08:35

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