Li J, Daniels G A, Lieber M R
Division of Molecular Oncology, and Center for Immunology, Washington University School of Medicine, St Louis, MO 63110, USA.
Nucleic Acids Res. 1996 Jun 1;24(11):2104-11. doi: 10.1093/nar/24.11.2104.
Junctions at class switch recombination sites in the genome are characterized by a unique sequence feature. Nucleotide substitutions and small deletions are common on either of the two sides of the switch junction, but not on both together. We have previously reported an extrachromosomal substrate assay system for analyzing the recombination of class switch sequences. Here we have sequenced nine junctions on each side of the break point and compared these to 17 recombination junctions of control substrates from the same cells. Five of the nine switch recombination junctions have nucleotide substitutions and deletions, with multiple nucleotide changes being more common. Furthermore, mutations were found only on a single side of the junction, just as for the recombination of switch sequences in the genome. In contrast, only one of 17 control substrate junctions had a mutation, and this was a single nucleotide insertion. This difference is highly significant (P < 0.00007) and indicates that the fundamental recombination mechanism is likely to be similar for switch sequences in the chromosome and on minichromosome substrates.
基因组中类别转换重组位点处的连接具有独特的序列特征。核苷酸替换和小片段缺失在转换连接两侧的任一侧都很常见，但不会同时出现在两侧。我们之前报道过一种用于分析类别转换序列重组的染色体外底物检测系统。在此，我们对断点两侧的九个连接进行了测序，并将其与来自同一细胞的对照底物的17个重组连接进行比较。九个转换重组连接中有五个存在核苷酸替换和缺失，多个核苷酸变化更为常见。此外，正如基因组中转换序列的重组情况一样，突变仅出现在连接的一侧。相比之下，17个对照底物连接中只有一个发生了突变，且是单个核苷酸插入。这种差异具有高度显著性（P < 0.00007），表明染色体和微型染色体底物上的转换序列的基本重组机制可能相似。
