Ollo R, Rougeon F
Cell. 1983 Feb;32(2):515-23. doi: 10.1016/0092-8674(83)90471-3.
We have determined the complete nucleotide sequence of the C57BL/6 allele of the mouse immunoglobulin gamma 2a chain gene. A comparison with the BALB/c gamma 2a gene for 1912 nucleotides reveals that the two alleles exhibit extensive divergence, since there are 138 single-base-pair differences and 8 insertions or deletions. We have compared the two gamma 2a alleles with the two corresponding gamma 2b alleles, which differ in only 12 positions. It appears that among the 134 differences between the two gamma 2a alleles, 70 are at positions where gamma 2a and gamma 2b are identical in the BALB/c haplotype and 54 are at positions where gamma 2a and gamma 2b are identical in the C57BL/6 haplotype. All these results suggest that nonreciprocal gene conversion between nonallelic genes can introduce sequence homogeneity in linked genes and can generate extensive divergence and polymorphism in allelic genes. We suggest that the gamma 2a and gamma 2b gene ancestors freely diverged after duplication, and that the conversion events were promoted by a deletion shortening the distance between the two loci.
我们已经确定了小鼠免疫球蛋白γ2a链基因C57BL/6等位基因的完整核苷酸序列。将其与BALB/cγ2a基因的1912个核苷酸进行比较后发现，这两个等位基因存在广泛的差异，因为有138个单碱基对差异以及8处插入或缺失。我们还将这两个γ2a等位基因与两个相应的γ2b等位基因进行了比较，后者仅在12个位置存在差异。在两个γ2a等位基因之间的134个差异中，似乎有70个位于BALB/c单倍型中γ2a和γ2b相同的位置，54个位于C57BL/6单倍型中γ2a和γ2b相同的位置。所有这些结果表明，非等位基因之间的非相互基因转换可在连锁基因中引入序列同质性，并可在等位基因中产生广泛的差异和多态性。我们认为，γ2a和γ2b基因的祖先在复制后自由分化，并且缺失缩短了两个基因座之间的距离，从而促进了转换事件的发生。
