Keshet E, Itin A
J Virol. 1982 Jul;43(1):50-8. doi: 10.1128/JVI.43.1.50-58.1982.
The mouse genome contains over 100 copies of a dispersed gene family known as "virus-like" genes encoding 30S RNA (VL30). Although they do not share nucleotide sequence homology with known retroviruses, these genetic elements are distinguished by several "retrovirus-like" features, notably, the capacity of the 30S RNA transcripts of these genes to be encapsidated by c-type virions and the transmissibility of VL30 information to other cells via pseudovirion infection. Using VL30 DNA units, cloned from the BALB/c mouse embryonic gene library, we have recently shown that VL30 DNA units share basic structural features with retrovirus proviruses. To shed light on the relatedness of VL30 information to endogenous proviruses and possibly other genetic elements, we extended our previous studies concerning genomic distribution patterns of VL30 elements and patterns of sequence heterogeneity among VL30 units. The following observations were made: (i) VL30 units were distributed among different mouse chromosomes; (ii) distribution patterns of VL30 units markedly differed among mouse strains; (iii) there was constancy of VL30 restriction patterns in different tissues; (iv) a high degree of sequence divergence existed among different VL30 units cloned from the same embryo; and (v) VL30 units were heterogeneous with respect to the state of DNA methylation. The results are discussed in terms of the possible modes of evolution of this multigene family.
小鼠基因组包含一个称为“病毒样”基因的分散基因家族的100多个拷贝，这些基因编码30S RNA（VL30）。尽管它们与已知逆转录病毒没有核苷酸序列同源性，但这些遗传元件具有几个“逆转录病毒样”特征，特别是这些基因的30S RNA转录本能够被c型病毒体包裹，以及VL30信息通过假病毒感染传递到其他细胞的能力。利用从BALB/c小鼠胚胎基因文库中克隆的VL30 DNA单位，我们最近发现VL30 DNA单位与逆转录病毒前病毒具有基本的结构特征。为了阐明VL30信息与内源性前病毒以及可能的其他遗传元件之间的相关性，我们扩展了之前关于VL30元件基因组分布模式和VL30单位之间序列异质性模式的研究。得到了以下观察结果：（i）VL30单位分布在不同的小鼠染色体上；（ii）VL30单位的分布模式在不同小鼠品系之间明显不同；（iii）不同组织中VL30限制模式具有稳定性；（iv）从同一胚胎克隆的不同VL单位之间存在高度的序列差异；（v）VL30单位在DNA甲基化状态方面是异质的。我们根据这个多基因家族可能的进化模式对结果进行了讨论。
