Moshier J A, Deutch A H, Huang R C
Department of Biology, Johns Hopkins University, Baltimore, MD 21218.
Gene. 1987;58(1):19-27. doi: 10.1016/0378-1119(87)90025-4.
A highly repetitive DNA element located 950 bp upstream from a mouse U2 small nuclear RNA gene has been cloned and characterized. The repetitive element is composed of a simple sequence repeat and a cluster of three B1 sequences. Two of these B1 elements are arranged head-to-tail and are joined by an oligo(dA)-rich linker. This unique B1 dimer, comprised of 339 bp, resembles the dimeric structure of primate Alu-family sequences, particularly that of a prototypic human Alu element. The other B1 element within the mouse cluster is a typical monomeric unit. Transcription studies performed in HeLa cell extracts with deletion mutants of the B1 cluster reveal that the single B1 unit is expressed at least 50 times more efficiently than the B1 dimer region. Furthermore, the B1 dimer which contains mutations in the first polymerase III promoter region is not transcribed end-to-end. We conclude that this B1 dimer is unlikely to give rise to a new dimeric retroposon family in the mouse genome.
已克隆并鉴定了位于小鼠U2小核RNA基因上游950 bp处的一个高度重复DNA元件。该重复元件由一个简单序列重复和一组三个B1序列组成。其中两个B1元件头对头排列，并由富含寡聚(dA)的接头连接。这个由339 bp组成的独特B1二聚体类似于灵长类Alu家族序列的二聚体结构，特别是典型的人类Alu元件的结构。小鼠簇中的另一个B1元件是典型的单体单元。用B1簇的缺失突变体在HeLa细胞提取物中进行的转录研究表明，单个B1单元的表达效率至少比B1二聚体区域高50倍。此外，在第一个聚合酶III启动子区域含有突变的B1二聚体不能端对端转录。我们得出结论，这个B1二聚体不太可能在小鼠基因组中产生一个新的二聚体反转录转座子家族。
