Gerlach W L, Dyer T A
Nucleic Acids Res. 1980 Nov 11;8(21):4851-65. doi: 10.1093/nar/8.21.4851.
Examples of both the 410 and 500 bp size classes of repeating units containing wheat 5S rRNA genes have been cloned in plasmid pBR322 and sequenced. The structural genes showed sequence microheterogeneity. Also the gene in the 500 bp repeat which was sequenced had a 15 bp tandem duplication within it and appears to be representative of non-transcribed subfamily of repeating units. The transcription terminators comprise 14-17 A.T bp immediately preceded by a region of weak dyad symmetry. The spacer regions adjacent to the transcription terminators in the two different size repeat units have interspersed oligonucleotides of high and low homology. The central spacer regions of the two size classes have very different sequences. The only repeated sequence in the spacers has undergone extensive divergence. In contrast to most of the spacer, the 70 bp region preceding the genes of each type of repeat show high homology, suggesting that it has functional importance. The transcription start point obeys the pyrimidine-1 purine+1 rule.
包含小麦5S rRNA基因的410和500碱基对大小重复单元的例子已被克隆到质粒pBR322中并进行了测序。结构基因表现出序列微异质性。同样，被测序的500碱基对重复序列中的基因内部有一个15碱基对的串联重复，似乎代表了重复单元的非转录亚家族。转录终止子由紧接在弱二元对称区域之前的14 - 17个A.T碱基对组成。两种不同大小重复单元中与转录终止子相邻的间隔区有高同源性和低同源性相间的寡核苷酸。两种大小类别的中央间隔区有非常不同的序列。间隔区中唯一的重复序列已经发生了广泛的分化。与大多数间隔区不同，每种重复类型基因之前的70碱基对区域显示出高度同源性，表明它具有功能重要性。转录起始点遵循嘧啶-1嘌呤+1规则。
