Swift G, McCarthy B J, Heffron F
Mol Gen Genet. 1981;181(4):441-7. doi: 10.1007/BF00428733.
The sequence of the methotrexate-resistant dihydrofolate reductase (DHFR) gene borne by the plasmid R-388 was determined. The gene was subcloned and mapped by an in vitro mutagenesis method involving insertion of synthetic oligonucleotide decamers encoding the BamHI recognition site. Sites of insertion that destroyed the methotrexate resistance fell in two regions separated by 300 bp within a 1.2 kb fragment. One of these regions encodes a 78 amino acid polypeptide homologous to another drug-resistant DHFR. The second region essential for DHFR expression appears to be the promoter of the DHFR gene.
测定了质粒R - 388携带的甲氨蝶呤抗性二氢叶酸还原酶（DHFR）基因的序列。该基因通过一种体外诱变方法进行亚克隆和定位，该方法涉及插入编码BamHI识别位点的合成寡核苷酸十聚体。破坏甲氨蝶呤抗性的插入位点位于一个1.2 kb片段内两个相隔300 bp的区域。其中一个区域编码与另一种耐药性DHFR同源的78个氨基酸的多肽。DHFR表达所必需的第二个区域似乎是DHFR基因的启动子。
