Morgan G T, Middleton K M
Department of Genetics, University of Nottingham, Queens Medical Centre, Nottingham, UK.
Nucleic Acids Res. 1990 Oct 11;18(19):5781-6. doi: 10.1093/nar/18.19.5781.
We have identified in an intron of an X. laevis alpha-tubulin gene a member of a novel family of short (226-431 bp) interspersed repetitive elements. We have isolated other members of this family, which we term Ocr, from ovary cDNA and genome libraries and have identified another two in the published sequences of an H1B histone gene cluster and an actin gene intron. The termini of the Ocr elements are formed by a 19 bp inverted repeat that has clear sequence homologies to those of certain large transposable elements, such as 1723 (Xenopus) and Ac (maize). However, the Ocr elements do not appear to be deletion derivatives of larger transposons. The internal regions of the Ocr elements contain multiple copies of the octamer motif (ATTTGCAT) arranged as divergently-orientated dyads. We have shown by a gel mobility shift assay that these octamer dyads specifically bind what is presumably an OTF-type activator protein in oocyte nuclear extracts. We speculate that short interspersed repetitive families of this type may be generated by a mechanism of replicative transposition that uses a DNA intermediate and involves the interaction of DNA-binding proteins also utilised in other cellular processes.
我们在非洲爪蟾α-微管蛋白基因的一个内含子中鉴定出一个新的短（226 - 431 bp）散布重复元件家族的成员。我们从卵巢cDNA和基因组文库中分离出了该家族的其他成员，我们将其命名为Ocr，并在一个H1B组蛋白基因簇和一个肌动蛋白基因内含子的已发表序列中又鉴定出另外两个成员。Ocr元件的末端由一个19 bp的反向重复序列形成，该序列与某些大型转座元件（如1723（非洲爪蟾）和Ac（玉米））的序列具有明显的同源性。然而，Ocr元件似乎不是较大转座子的缺失衍生物。Ocr元件的内部区域包含多个八聚体基序（ATTTGCAT）的拷贝，这些拷贝以反向排列的二元组形式存在。我们通过凝胶迁移率变动分析表明，这些八聚体二元组在卵母细胞核提取物中特异性结合可能是OTF型激活蛋白的物质。我们推测，这种类型的短散布重复家族可能是由一种复制转座机制产生的，该机制使用DNA中间体，并涉及在其他细胞过程中也使用的DNA结合蛋白的相互作用。
