Paper Citing NAMD - Abstract
Dromey, J.A.; Weenink, S.M.; Peters, G.H.; Endl, J.; Tighe, P.J.; Todd, I.; Christie, M.R.
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, 172:4084-4090, APR 1 2004
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 I diabetic patient. This Ab competes for IA-2 binding with Abs from the majority of patients with type I 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 Asn(858), Glu(836), and Trp(799) 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.
