Sharp S, Garcia A, Cooley L, Söll D
Nucleic Acids Res. 1984 Oct 25;12(20):7617-32. doi: 10.1093/nar/12.20.7617.
Transcription of isolated repeat units of D. melanogaster 5S DNA in a Drosophila KcO cell extract revealed three types of template activities. 5SI DNA encodes the known 5S rRNA of D. melanogaster and has a relatively high transcription efficiency. 5SII DNA is identical to 5SI DNA except for a two-nucleotide deletion at 5S rRNA positions 28 and 29; the efficiency of transcription is approximately 40% that of 5SI DNA and because of the deletion, the primary transcript is two nucleotides shorter. 5SIII DNA does not support in vitro transcription (less than 2% 5SI DNA), but has the same sequence as 5SI DNA except for a single G to A transition at position 86. This is the first reported point-mutation in a 5S RNA gene resulting in loss of transcription function. Of approximately 23 5S rRNA gene copies in a cloned 5S DNA sub-cluster (p12D1) 19 appear to be of the transcriptionally inactive 5SIII DNA type.
在果蝇KcO细胞提取物中对黑腹果蝇5S DNA的分离重复单元进行转录，发现了三种类型的模板活性。5SI DNA编码黑腹果蝇已知的5S rRNA，转录效率相对较高。5SII DNA与5SI DNA相同，只是在5S rRNA的第28和29位有两个核苷酸缺失；转录效率约为5SI DNA的40%，由于缺失，初级转录本短两个核苷酸。5SIII DNA不支持体外转录（不到5SI DNA的2%），但除了在第86位有一个单一的G到A转换外，其序列与5SI DNA相同。这是首次报道的5S RNA基因中的点突变导致转录功能丧失。在一个克隆的5S DNA亚簇（p12D1）中约23个5S rRNA基因拷贝中，19个似乎是转录无活性的5SIII DNA类型。
