Bentley D L, Rabbitts T H
Cell. 1983 Jan;32(1):181-9. doi: 10.1016/0092-8674(83)90508-1.
We have analyzed several closely related members of the gene family encoding the variable regions of human immunoglobulin kappa light chains (V kappa genes). Two of these genes differ at a single nucleotide out of 940 bases sequenced, and are believed to be alleles of a locus called HK 101. This substitution results in an amino acid replacement in the first complementarity-determining region of the kappa chain. We also compared the structures of two nonallelic human V kappa loci (HK 101 and HK 137) and found a high degree of sequence homology over a region at least 13.5 kb long. This long block of homology indicates that these two loci arose from a recent gene duplication. The DNA sequences of these two nonallelic V kappa genes exhibit a very unusual distribution of nucleotide substitutions. Seven of the ten substitutions found among 940 bases are clustered in a 39 base stretch encoding the first complementarity-determining region and the second framework region of the protein. We suggest that this cluster of substitutions was generated by a gene conversion in which a small segment of one gene was replaced with the homologous segment from another V kappa gene.
我们分析了编码人类免疫球蛋白κ轻链可变区（Vκ基因）的基因家族中几个密切相关的成员。在已测序的940个碱基中，其中两个基因仅有一个核苷酸不同，被认为是一个名为HK 101位点的等位基因。这种替换导致κ链的第一个互补决定区出现氨基酸替换。我们还比较了两个非等位人类Vκ位点（HK 101和HK 137）的结构，发现在至少13.5 kb长的区域内存在高度的序列同源性。这种长片段的同源性表明这两个位点源于近期的基因复制。这两个非等位Vκ基因的DNA序列呈现出非常不寻常的核苷酸替换分布。在940个碱基中发现的10个替换中有7个聚集在一段39个碱基的区域内，该区域编码蛋白质的第一个互补决定区和第二个框架区。我们认为这种替换簇是由基因转换产生的，其中一个基因的一小段被另一个Vκ基因的同源片段所取代。
