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首页> 外文期刊>Molecular and Cellular Biology >Human U1 RNA pseudogenes may be generated by both DNA- and RNA-mediated mechanisms.
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Human U1 RNA pseudogenes may be generated by both DNA- and RNA-mediated mechanisms.

机译：人U1 RNA假基因可以通过DNA和RNA介导的机制生成。

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Analysis of cloned human genomic loci homologous to the small nuclear RNA U1 established that such sequences are abundant and dispersed in the human genome and that only a fraction represent bona fide genes. The majority of genomic loci bear defective gene copies, or pseudogenes, which contain scattered base mismatches and in some cases lack the sequence corresponding to the 3' end of U1 RNA. Although all of the U1 genes examined to date are flanked by essentially identical sequences and therefore appear to comprise a single multigene family, we present evidence for the existence of at least three structurally distinct classes of U1 pseudogenes. Class I pseudogenes had considerable flanking sequence homology with the U1 gene family and were probably derived from it by a DNA-mediated event such as gene duplication. In contrast, the U1 sequence in class II and III U1 pseudogenes was flanked by single-copy genomic sequences completely unrelated to those flanking the U1 gene family; in addition, short direct repeats flanked the class III but not the class II pseudogenes. We therefore propose that both class II and III U1 pseudogenes were generated by an RNA-mediated mechanism involving the insertion of U1 sequence information into a new chromosomal locus. We also noted that two other types of repetitive DNA sequences in eucaryotes, the Alu family in vertebrates and the ribosomal DNA insertions in Drosophila, bore a striking structural resemblance to the classes of U1 pseudogenes described here and may have been created by an RNA-mediated insertion event.
机译：对与小核RNA U1同源的克隆的人类基因组位点的分析证实，此类序列丰富且分散在人类基因组中，并且只有一部分代表了真正的基因。大多数基因组位点带有缺陷的基因拷贝或假基因，其包含分散的碱基错配，在某些情况下缺少对应于U1 RNA 3'末端的序列。尽管迄今为止检查的所有U1基因均侧接基本相同的序列，因此似乎包含一个单一的多基因家族，但我们为至少三个U1假基因在结构上不同的类的存在提供了证据。 I类假基因与U1基因家族有相当大的侧翼序列同源性，可能是通过DNA介导的事件（如基因复制）从中衍生而来的。相比之下，II和III类U1假基因中的U1序列侧翼是与U1基因家族侧翼完全不相关的单拷贝基因组序列。此外，短的直接重复序列位于III类假基因的侧面，而不是II类假基因的侧面。因此，我们提出II类和III类U1假基因都是由RNA介导的机制产生的，该机制涉及将U1序列信息插入新的染色体基因座。我们还注意到，真核生物中的其他两种重复DNA序列，脊椎动物中的Alu家族和果蝇中的核糖体DNA插入，​​与此处描述的U1假基因类别具有惊人的结构相似性，可能是由R​​NA介导的插入事件。

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