Identification of an immunodominant region on the I-A beta chain using site-directed mutagenesis and DNA-mediated gene transfer.
To identify which polymorphic residues determine the allospecific antibody binding sites on A beta polypeptides, mutant Ak beta genes were constructed encoding single or multiple amino acids of the d allele at 14 polymorphic positions in the beta 1 domain. Cell lines expressing these genes were analyzed by quantitative immunofluorescence using 16 mAbs reactive to Ak beta or Ad beta. Substitution of d allele residues at positions 63 and 65-67 in the Ak beta polypeptide resulted in the loss of binding of all Ak beta-reactive antibodies and the gain of binding of most Ad beta-reactive antibodies. Two Ad beta-reactive mAbs bound to the mutant Ak beta polypeptide containing d allele-characteristic residue at position 40. In contrast, substitution of the other polymorphic residues in the NH2-terminal and COOH-terminal regions of the beta 1 domain did not alter antibody binding.
D000595:Amino Acid Sequence; D000818:Animals; D001666:Binding Sites, Antibody; D004247:DNA / Q000502:physiology*; D000939:Epitopes / Q000032:analysis; D005799:Genes, Dominant; D000949:Histocompatibility Antigens Class II / Q000032:analysis / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000032:analysis / Q000235:genetics; D011110:Polymorphism, Genetic; D014162:Transfection
D000939:Epitopes; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D004247:DNA