title: Genetics and primary structure of V kappa gene segments encoding antibody to streptococcal group A carbohydrate. Comparison of V kappa gene structure with idiotope expression.
abstract: Two gene segments, V kappa-25-39 and V kappa-25-47, that encode antibody to streptococcal group A carbohydrate in A/J mice were found to be more than 95% homologous in nucleotide sequence in both coding and noncoding regions. It was previously shown that V kappa-25-39 encodes immunoglobulins that express the IdX and IdI-1 idiotopes, whereas V kappa-25-47 encodes IdX+, and IdI-1- immunoglobulins. V kappa gene segments that were clearly allelic to V kappa-25-47 are used to encode IdX+, IdI-1- anti-group A carbohydrate antibodies by C.B20 mice and likely by C57BL/6 mice. Murine strains that are deficient in IdI-1 idiotope expression were investigated by Southern blotting with a 5' probe from V kappa-25-39. Two IdI-1-deficient strains, CE/J and C58/J, had a grossly altered V kappa gene segment structure compared with the A/J prototype. In contrast, the IdI-1-deficient strain, C57BL/6, was indistinguishable from A/J with the 5'V kappa-25-39 probe, indicating that more subtle genetic changes account for the loss of IdI-1 expression in C57BL/6 mice. The evolution of V kappa-25-39 and V kappa-25-47 gene segments was deduced by comparison with the homologous V kappa 24B gene segment of Mus pahari. V kappa-25-39 and V kappa-25-47 likely have recently duplicated once in A/J and related strains of laboratory mice and may have duplicated again in CE/J mice. Thus, individual members of the V kappa 24 gene family, to which V kappa-25-39 and V kappa-25-47 belong, are preserved while the number of gene copies expands or contracts. This fact is strong evidence that evolutionary forces have maintained the V kappa 24 gene family, all of which encode antibody specific for carbohydrate found in bacterial pathogens.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000235:genetics*; D001483:Base Sequence; D005803:Genes, Immunoglobulin; D007130:Immunoglobulin Idiotypes / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D007153:Immunologic Deficiency Syndromes / Q000235:genetics; D051379:Mice; D008805:Mice, Inbred A / Q000235:genetics; D008807:Mice, Inbred BALB C / Q000235:genetics; D008810:Mice, Inbred C57BL / Q000235:genetics; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000907:Antibodies, Bacterial; D007130:Immunoglobulin Idiotypes; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D011135:Polysaccharides, Bacterial; C036112:streptococcal polysaccharide group A