Piper P W, Lockheart A, Patel N
Nucleic Acids Res. 1984 May 25;12(10):4083-96. doi: 10.1093/nar/12.10.4083.
In Saccharomyces cerevisiae the majority of the genes for 5S rRNA lie within a 9kb rDNA sequence that is present as 100-200 tandemly-repeated copies on Chromosome XII. Following our observations that about 10% of yeast 5S rRNA exists as minor variant sequences, we screened a collection of yeast DNA fragments cloned in lambda gt for 5S rRNA genes whose flanking sequences differed from those adjacent to 5S rRNA genes of the rDNA repeat. Three variant 5S rRNA genes were isolated on the basis of such dissimilarity to rDNA repeat sequences. They display a remarkable conservation of their DNA in the vicinity of the 5S coding region, and are examples of a minor form of 5S rRNA coding sequence present in a small number of copies in the yeast genome. These variant sequences appear to be transcribed as efficiently as 5S rRNA genes of the rDNA repeat. In one of our isolates of the variant sequence a Ty transposable element is inserted 145bp upstream of the initiation point for 5S rRNA synthesis.
在酿酒酵母中，大多数5S rRNA基因位于一个9kb的rDNA序列内，该序列以100 - 200个串联重复拷贝的形式存在于第十二号染色体上。在我们观察到约10%的酵母5S rRNA以次要变异序列形式存在之后，我们筛选了一组克隆于λgt的酵母DNA片段，寻找其侧翼序列与rDNA重复序列中5S rRNA基因相邻序列不同的5S rRNA基因。基于与rDNA重复序列的这种差异，分离出了三个变异的5S rRNA基因。它们在5S编码区附近的DNA具有显著的保守性，是酵母基因组中少量拷贝存在的5S rRNA编码序列的一种次要形式的实例。这些变异序列的转录效率似乎与rDNA重复序列中的5S rRNA基因相同。在我们分离出的一个变异序列中，一个Ty转座元件插入到了5S rRNA合成起始点上游145bp处。
