The Ig kappa L chain allelic groups among the Ig kappa haplotypes and Ig kappa crossover populations suggest a gene order

Abstract

The Ig kappa complex locus of inbred mice found on chromosome 6 contains one constant (C kappa), five joining (J kappa), and 100 to 300 variable (V kappa) exons and spans an estimated 500 to 2000 kbp of DNA. The V kappa exons are organized into groups of highly homologous coding regions (approximately 300 bp) separated by approximately 10 kbp of intervening sequence. A group contains from 1 to 30 or more exons (exon refers to uninterrupted coding region DNA which is capable of encoding all or part of V kappa gene) that can be detected with specific DNA probes in conjunction with restriction endonuclease fragments (REF) from genomic DNA. Thirteen DNA probes specific for different V kappa exon groups and one DNA probe specific for J kappa and C kappa exons were used in conjunction with 55 inbred strains in an attempt to detect RFLP that could be used to establish Ig kappa allelic groups and Ig kappa haplotypes. Each probe detected two to four different REF patterns (allelic groups) among the panel of inbred mice examined. Size estimates of the REF were made, and each probe detected 4.2 to 107.7 kbp of DNA, including faint REF, 675.6 to 723.6 kbp of DNA could be detected within a single haplotype. Based on these allelic groups, seven haplotypes were identified among the 55 inbred strains of mice. No subline differences were detected, and the distribution of allelic groups implied common ancestry among many of the inbred strains examined. The DNA probes were also used in conjunction with recombinant inbred, congenic strains and backcross populations of mice. By using the analysis of known Ig kappa r populations, and assuming a common ancestry among the inbred strains, a gene order was predicted: Centromere-Hd-(Ig kappa-V11, Ig kappa-V24, Ig kappa-V9-26)-(Ig kappa-V1, Ig kappa-V9)-(Ig kappa-V4, Ig kappa-V8, Ig kappa-V10, Ig kappa-V12, 13, Ig kappa-V19)-(Ig kappa-V28, Rn7s-6)-Ig kappa-V23-(Ig kappa-V21, Ig kappa-J, Ig kappa-C)-(Ly2, Ly3)-wa-1.