Carter A T, Norton J D, Avery R J
Department of Biological Sciences, University of Warwick, Coventry, U.K.
Biochim Biophys Acta. 1988 Nov 10;951(1):130-8. doi: 10.1016/0167-4781(88)90033-4.
The sequence organisation of endogenous VL30 elements in the mouse genome was investigated by using a cloned representative of a retrovirus-transmissible VL30 cDNA. The majority of dispersed VL30 sequences could be assigned to a proviral-like structure 5.2-5.3 kbp long and bounded by long terminal repeats (LTRs). The existence of a hierarchy of evolutionarily conserved elements was rather limited and sequence heterogeneity between different elements was randomly distributed. However, the retrovirus-transmissible class of VL30 element was found to represent a distinct minority subgroup distinguishable by restriction sites and size (4.6-4.9 kbp long). Analysis of sequence conservation showed that VL30 elements display a more rapid turnover than endogenous murine leukaemia virus-related proviral sequences, and that VL30 LTRs show the most limited evolutionary distribution. Although discrete subsets of VL30 unique sequence were conserved in different rodents, the location of conserved regions was found to be variable, arguing against the presence of a functionally conserved protein coding region. These observations support the hypothesis that high frequency recombination, probably occurring during reverse transcription and the accompanying processes of duplicative transposition and amplification, have been a major determinant in the mode of evolution of the VL30 gene family.
通过使用一种可经逆转录病毒传播的VL30 cDNA的克隆代表，对小鼠基因组中内源性VL30元件的序列组织进行了研究。大多数分散的VL30序列可归为一种长度为5.2 - 5.3 kbp、由长末端重复序列（LTRs）界定的前病毒样结构。进化保守元件层次结构的存在相当有限，不同元件之间的序列异质性是随机分布的。然而，发现可经逆转录病毒传播的VL30元件类别代表一个独特的少数亚组，可通过限制性酶切位点和大小（4.6 - 4.9 kbp长）区分。序列保守性分析表明，VL30元件的更新速度比内源性鼠白血病病毒相关前病毒序列更快，并且VL30 LTRs的进化分布最为有限。尽管VL30独特序列的离散子集在不同啮齿动物中是保守的，但发现保守区域的位置是可变的，这表明不存在功能保守的蛋白质编码区域。这些观察结果支持了这样一种假设，即高频重组，可能发生在逆转录以及伴随的重复转座和扩增过程中，是VL30基因家族进化模式的主要决定因素。
