Nickrent D L, Sargent M L
Department of Plant Biology, University of Illinois, Urbana 61801.
Nucleic Acids Res. 1991 Jan 25;19(2):227-35. doi: 10.1093/nar/19.2.227.
The V4 region of the small subunit (18S) ribosomal RNA was examined in 72 different sequences representing a broad sample eukaryotic diversity. This domain is the most variable region of the 18S rRNA molecule and ranges in length from ca. 230 to over 500 bases. Based upon comparative analysis, secondary structural models were constructed for all sequences and the resulting generalized model shows that most organisms possess seven helices for this region. The protists and two insects show from one to as many as four helices in addition to the above seven. In this report, we summarize secondary structure information presented elsewhere for the V4 region, describe the general features for helical and apical regions, and identify signature sequences useful in helix identification. Our model generally agrees with other current concepts; however, we propose modifications or alternative structures for the start of the V4 region, the large protist inserts, and the sector that may possibly contain a pseudoknot.
对代表广泛真核生物多样性的72个不同序列中的小亚基（18S）核糖体RNA的V4区域进行了研究。该结构域是18S rRNA分子中变化最大的区域，长度范围约为230至500多个碱基。基于比较分析，为所有序列构建了二级结构模型，所得的通用模型表明，大多数生物在该区域拥有七个螺旋。原生生物和两种昆虫除上述七个螺旋外，还显示出一到四个螺旋。在本报告中，我们总结了其他地方给出的V4区域的二级结构信息，描述了螺旋和顶端区域的一般特征，并确定了有助于螺旋识别的特征序列。我们的模型总体上与当前的其他概念一致；然而，我们对V4区域的起始部分、原生生物的大插入片段以及可能包含假结的区域提出了修改或替代结构。
