Characterization of allelic V kappa-1 region genes in inbred strains of mice.

Germ line genes encoding mouse Ig kappa-chains belonging to the V kappa-1 group have been isolated from BALB/c, NZB, and CE, three inbred strains of differing kappa haplotype. The V kappa-1A and V kappa-1C germ line genes isolated from BALB/c (Ig kappa c) were identical to those previously described. These are the two major V kappa-1 germ line genes in BALB/c and together account for 40 of the 53 expressed V kappa-1 sequences that have been reported to date. Allelic differences in a single germ line variable region gene (V kappa-1A) in different strains of mice explain the differences in L chain IEF patterns previously associated with the Ig kappa-Ef2 locus. The rearranged kappa-gene expressed in the BALB/c myeloma MOPC-460 has been isolated and found to represent a V kappa-1A somatic variant differing by three nucleotides from the germ line V kappa-1A gene. Germ line genes isolated from NZB (Ig kappa b) and CE (Ig kappa f) show greater than 95% identity with the BALB/c genes over the 1700 nucleotides compared. Comparison by region indicated the greatest conservation of sequence occurs in and around the leader exon followed by the V-region exon. The NZB gene encodes the amino acid sequence found in the myeloma PC-2205, previously designated V kappa-1B. The V kappa-1 gene isolated from CE is likely an allele of the BALB/c V kappa-1C gene as the two share greater than 96% identity over 1700 nucleotides. The CE gene has been designated V kappa-1Cf. Ancient remnants of LINE-1 repetitive elements were detected approximately 400 bp downstream of all of the V kappa-1 genes. These possess greater homology with repetitive elements found near other kappa genes than they do with the native L1Md sequence.