Kuo B A, Gonzalez I L, Gillespie D A, Sylvester J E
Department of Pathology and Laboratory Medicine, Medical College of Pennsylvania, Philadelphia 19102, USA.
Nucleic Acids Res. 1996 Dec 1;24(23):4817-24. doi: 10.1093/nar/24.23.4817.
We have investigated the extent of sequence variation in human ribosomal RNA (rRNA) genes and the expression of specific rRNA gene variants in different tissues of an individual. Focusing on the fifth variable region (V5; nt 2065-2244) of the 28S rRNA gene, we find that sequence differences between rRNA genes of a single individual are characterized by differences in number of repeats of simple sequences at four specific sites. These data support and extend previous findings which show similar V5 sequence variation in rRNA genes from a group of individuals. We performed experiments to determine if there is differential gene expression within the rRNA multigene family. From the analysis of data of six variant V5 probes protected from RNase digestion by rRNAs isolated from different tissues of the individual, we conclude that each variant rRNA is present in a similar proportion in these tissues, whereas the actual contributions of variants differ, their relative proportion is maintained from tissue to tissue in an individual. We favor the explanation of a gene dosage effect over that of a regulated gene effect to account for this pattern of rRNA gene expression. In addition, computer generated secondary structure models of each V5 clone structure predict the same three helix structure with the regions of sequence variation contained in one stem-loop structure.
我们研究了人类核糖体RNA（rRNA）基因的序列变异程度，以及个体不同组织中特定rRNA基因变体的表达情况。聚焦于28S rRNA基因的第五可变区（V5；核苷酸2065 - 2244），我们发现单个个体的rRNA基因之间的序列差异表现为四个特定位点处简单序列重复次数的差异。这些数据支持并扩展了先前的研究结果，即一组个体的rRNA基因中存在类似的V5序列变异。我们进行了实验以确定rRNA多基因家族内是否存在差异基因表达。通过对从个体不同组织分离的rRNA保护的六个变体V5探针的RNase消化数据进行分析，我们得出结论，每个变体rRNA在这些组织中的比例相似，然而变体的实际贡献不同，在个体中它们的相对比例在不同组织间保持不变。我们倾向于用基因剂量效应而非调控基因效应来解释这种rRNA基因表达模式。此外，每个V5克隆结构的计算机生成的二级结构模型预测出相同的三螺旋结构，序列变异区域包含在一个茎环结构中。
