Synthetic mimics of juxtaposed amino- and carboxyl-terminal peptide domains of human gamma interferon block ligand binding to human gamma interferon receptor.
The epitopes of two neutralizing antibodies (47N3-6 and 47N30A35) raised against rhuIFN-gamma each mapped both to amino-terminal regions (22-29 and 12-19, respectively) and to a carboxyl-terminal region 131-139, suggesting the juxtaposition of these two domains in the native protein. Three novel peptides were designed to mimic a conformation of rhuIFN-gamma that places the two regions in close proximity (discontinuous peptides 1 (15-21-GGG-132-138), 2 (15-29...111-118...130-138), and 3 (15-21-CGPGC-130-138)), by bridging the amino- and carboxyl-terminal regions of gamma interferon. Each discontinuous peptide inhibits biological or receptor binding activities with an IC50 of 15-50 microM and produces a neutralizing antibody when used as an immunogen. Neutralizing rabbit polyclonal antibody (P616) raised against discontinuous peptide 1 was used as immunogen to generate an anti-idiotypic response. This anti-idiotypic antibody inhibits receptor binding and recognizes soluble gamma interferon receptor on direct enzyme-linked immunosorbent assay. The anti-idiotypic response suggests that juxtaposed regions at the amino and carboxyl termini serve as the receptor-ligand binding site of human gamma interferon.
Seelig
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Schering-Plough Research Institute, Kenilworth, New Jersey 07033-0539.
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Taremi
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D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D000939:Epitopes; D006801:Humans; D007371:Interferon-gamma / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism*; D011817:Rabbits; D017471:Receptors, Interferon / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000096743:Interferon gamma Receptor
D000906:Antibodies; D000911:Antibodies, Monoclonal; D000939:Epitopes; D007371:Interferon-gamma; D008024:Ligands; D010446:Peptide Fragments; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor