Peculis B A, DeGregorio S, McDowell K
National Institutes of Health, NIDDK, Genetics and Biochemistry Branch, 10 Center Drive, 8N322, Bethesda, MD 20892-1766, USA.
Gene. 2001 Aug 22;274(1-2):83-92. doi: 10.1016/s0378-1119(01)00596-0.
U8 snoRNA is the RNA component of a small nucleolar ribonucleoprotein (U8 snoRNP) required for accumulation of mature 5.8S and 28S rRNAs, components of the large ribosomal subunit. We have identified two putative U8 genes in Xenopus laevis. Sequence analysis of the coding regions of these two genes indicate that both differ at several positions from the previously characterized U8 RNA and that the two differ from each other. Functional analysis of these genes indicates that both are transcribed in vivo, produce stable U8 transcripts, and are capable of facilitating pre-rRNA processing in vivo. These data demonstrate that natural sequence variation exists among the U8 snoRNA genes in Xenopus. Alignment of these three Xenopus U8 sequences with the previously described mammalian U8 homologues in mouse, rat and human has provided information about evolutionarily conserved sequence and structural elements in U8 RNA. Identification and functional characterization of these naturally occurring variants in Xenopus has helped identify regions in U8 RNA that may be critical for function.
U8小核仁RNA是小核仁核糖核蛋白（U8小核仁核糖核蛋白颗粒）的RNA组分，成熟的5.8S和28S核糖体RNA（大核糖体亚基的组分）的积累需要该蛋白。我们在非洲爪蟾中鉴定出了两个推定的U8基因。对这两个基因编码区的序列分析表明，二者在几个位置上与先前鉴定的U8 RNA不同，且二者之间也存在差异。对这些基因的功能分析表明，二者均在体内转录，产生稳定的U8转录本，并且能够在体内促进前体核糖体RNA加工。这些数据表明，非洲爪蟾的U8小核仁RNA基因之间存在自然序列变异。将这三个非洲爪蟾U8序列与先前描述的小鼠、大鼠和人类的哺乳动物U8同源物进行比对，提供了有关U8 RNA中进化保守序列和结构元件的信息。对非洲爪蟾中这些天然存在的变体进行鉴定和功能表征，有助于确定U8 RNA中可能对功能至关重要的区域。
