Benatar T, Ratcliffe M J
Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.
Eur J Immunol. 1993 Oct;23(10):2448-53. doi: 10.1002/eji.1830231011.
We have isolated a number of new allelic variants of the unique functional genes encoding chicken immunoglobulin heavy and light chain variable regions (VH1 and VL1, respectively). The distribution and nature of nucleotide variation among these and previously identified VH1 and VL1 alleles demonstrates that random point mutations are likely not the predominant cause of allelic variation at these loci. Comparison of the variant nucleotides with sequences from the pseudo-VH and pseudo-VL gene families, which lie 5' to VH1 and VL1, respectively, suggests that the great majority of allelic variants can be accounted for by segmental transfer of sequence from donor pseudogenes into the germ-line VH1 and VL1 genes. These results demonstrate that the chicken VH1 and VL1 genes are susceptible to sequence replacement at the germ-line level as well as somatically during antibody diversification. The limited repertoire of B cell specificities produced by gene rearrangement in the chicken has led to speculation that these specificities may play a critical role in the progression of chicken B cell development. The results presented here do not support this hypothesis since many of the allelic variant nucleotides described here encode non-conservative amino acid substitutions within the antigen-binding sites of the Ig molecule.
我们已经分离出了一些编码鸡免疫球蛋白重链和轻链可变区（分别为VH1和VL1）的独特功能基因的新等位基因变体。这些以及先前鉴定的VH1和VL1等位基因之间核苷酸变异的分布和性质表明，随机点突变可能不是这些位点等位基因变异的主要原因。将变体核苷酸与分别位于VH1和VL1上游5'的假VH和假VL基因家族的序列进行比较，结果表明，绝大多数等位基因变体可以通过供体假基因的序列片段转移到种系VH1和VL1基因中来解释。这些结果表明，鸡VH1和VL1基因在种系水平以及抗体多样化过程中的体细胞水平上都易于发生序列替换。鸡基因重排产生的有限的B细胞特异性库引发了这样的推测，即这些特异性可能在鸡B细胞发育进程中起关键作用。此处给出的结果并不支持这一假设，因为此处描述的许多等位基因变体核苷酸在Ig分子的抗原结合位点内编码非保守氨基酸取代。
