Non‐random features of the repertoire expressed by the members of one Vxgene family and of the V‐J recombination

摘要

AbstractThe 5' and 3' flanking sequences of 14 members of the VxOx (VK 4/5) gene family of BALB/c mice have been established. The family was unusual in the number of bases between the codon for Pro 95 and the heptamer sequence; most members contained four but there were also examples of none. A conserved leader sequence was used toamplify the genomic DNA of rearranged genes in order to analyze the spleen B cell repertoire of non‐immunized animals. The library contained many members with virtually identical sequences to one or other of the already known members of the family. In addition, there were repeats of other sequences, allowing the definition of 12 hitherto undefined members of the family. Only 3 out of 96 could have originated by gene conversion, or as artefacts of the amplification procedure, and only 2 were putative somatic mutants.The frequency of expression of different members of the VxOx gene family was not random, and some germ‐line genes were unrepresented in the library. The high frequency of VxOx1‐Jx5 is in line with the dominance of this combination in the oxazolone response.An analysis of the junctional segment showed that although in most cases the diversity was due to trimming, there were exceptions indicatingde novoadditions (N or P bases). The average number of bases trimmed from the Vxand the Jxsegments was not the same. There was no correlation in the number of bases trimmed from Vxor Jxin each recombination. The implications of asymmetric trimming in terms of the mechanism of recombination are disc