Samarsky D A, Schneider G S, Fournier M J
Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA.
Nucleic Acids Res. 1996 Jun 1;24(11):2059-66. doi: 10.1093/nar/24.11.2059.
U14 is a small nucleolar RNA (snoRNA) required for early cleavages of eukaryotic precursor rRNA. The U14 RNA from Saccharomyces cerevisiae is distinguished from its vertebrate homologues by the presence of a stem-loop domain that is essential for function. This element, known as the Y-domain, is located in the U14 sequence between two universal sequences that base pair with 18S rRNA. Sequence data obtained for the U14 homologues from four additional phylogenetically distinct yeasts showed the Y-domain is not unique to S.cerevisiae. Comparison of the five Y-domain sequences revealed a common stem-loop structure with a conserved loop sequence that includes eight invariant nucleotides. Conservation of these features suggests that the Y-domain is a recognition signal for an essential interaction. Several plant U14 RNAs were found to contain similar structures, though with an unrelated consensus sequence in the loop portion. The U14 gene from the most distantly related yeast, Schizosaccharomyces pombe, was found to be active in S.cerevisiae, showing that Y-domain function is conserved and that U14 function can be provided by variants in which the essential elements are embedded in dissimilar flanking sequences. This last result suggests that U14 function may be determined solely by the essential elements.
U14是一种小核仁RNA（snoRNA），是真核生物前体rRNA早期切割所必需的。酿酒酵母的U14 RNA与其脊椎动物同源物的区别在于存在一个对功能至关重要的茎环结构域。这个元件，即Y结构域，位于U14序列中与18S rRNA碱基配对的两个通用序列之间。从另外四种系统发育上不同的酵母中获得的U14同源物的序列数据表明，Y结构域并非酿酒酵母所独有。对五个Y结构域序列的比较揭示了一种常见的茎环结构，其环序列保守，包括八个不变核苷酸。这些特征的保守性表明Y结构域是一种必需相互作用的识别信号。发现几种植物U14 RNA含有类似结构，尽管其环部分的共有序列无关。发现来自亲缘关系最远的酵母粟酒裂殖酵母的U14基因在酿酒酵母中具有活性，这表明Y结构域功能是保守的，并且U14功能可以由其中必需元件嵌入不同侧翼序列的变体提供。最后这个结果表明，U14功能可能仅由必需元件决定。
