Harashima S, Shimada Y, Oshima Y
Mol Gen Genet. 1985;199(1):14-20. doi: 10.1007/BF00327503.
A yeast mutant plasmid, pX, showing increased stability of holding in mitotic and meiotic cell division, was isolated from an unstable plasmid, YRp7, which consists of pBR322 and a 1.4 kilobase (kb) fragment of Saccharomyces cerevisiae carrying the TRP1 gene and the autonomously replicating sequence, ARS1. The pX plasmid exists as circular molecules in a series of polymeric forms from the monomer to the 20-mer or more, consisting, except for the monomer, of even numbers of unit molecules in tandem arrangement. The pX monomer consists solely of a yeast DNA fragment of 849 base pairs (bp) containing the TRP1 and ARS1 sequences derived from the 1.4 kb yeast fragment of YRp7. The copy number of pX was calculated to be 20 as monomer units per genome. The ARS1 region was delimited to 80 bp by this mutation and the region essential for the ARS function was discussed.
从不稳定质粒YRp7中分离出一种酵母突变体质粒pX，它在有丝分裂和减数分裂细胞分裂中表现出更高的稳定性。YRp7由pBR322和一个携带TRP1基因及自主复制序列ARS1的1.4千碱基（kb）酿酒酵母片段组成。pX质粒以环状分子形式存在，呈从单体到20聚体或更多的一系列聚合形式，除单体外，由偶数个单位分子串联排列组成。pX单体仅由一个849碱基对（bp）的酵母DNA片段组成，该片段包含源自YRp7的1.4 kb酵母片段的TRP1和ARS1序列。计算得出pX的拷贝数为每个基因组20个单体单位。通过该突变将ARS1区域界定为80 bp，并对ARS功能所必需的区域进行了讨论。
