Ligtenberg M J, Gennissen A M, Vos H L, Hilkens J
Division of Tumor Biology, The Netherlands Cancer Institute (Antoni van Leeuwenhoekhuis), Amsterdam.
Nucleic Acids Res. 1991 Jan 25;19(2):297-301. doi: 10.1093/nar/19.2.297.
The episialin gene (MUC1) encodes an epithelial mucin containing a variable number of repeats with a length of twenty amino acids, resulting in many different alleles that can be subdivided into two size classes. The episialin pre-mRNA uses either one of two neighbouring splice acceptor sites for exon 2, which mainly encodes the repeats. Using the genetic polymorphism of the episialin gene to identify different alleles, we show here that the splice site recognition is allele dependent and is based on a single A/G nucleotide difference in exon 2 eight nucleotides downstream of the second splice acceptor site. Transfection experiments confirm that this polymorphic nucleotide regulates the splice site selection. The identity of this nucleotide is in most cases correlated with one of the size classes of the alleles, indicating that mutations altering the number of repeats seldom arise by unequal cross-over between the repeat regions.
表层上皮糖蛋白基因（MUC1）编码一种上皮粘蛋白，该粘蛋白含有可变数量的长度为20个氨基酸的重复序列，从而产生许多不同的等位基因，这些等位基因可细分为两个大小类别。表层上皮糖蛋白前体mRNA使用外显子2的两个相邻剪接受体位点之一，外显子2主要编码重复序列。利用表层上皮糖蛋白基因的遗传多态性来鉴定不同的等位基因，我们在此表明剪接位点识别是等位基因依赖性的，并且基于第二个剪接受体位点下游八个核苷酸处外显子2中的单个A/G核苷酸差异。转染实验证实该多态性核苷酸调节剪接位点选择。在大多数情况下，该核苷酸的身份与等位基因的大小类别之一相关，这表明改变重复序列数量的突变很少通过重复区域之间的不等交换产生。
