Debatisse M, de Saint Vincent B R, Buttin G
EMBO J. 1984 Dec 20;3(13):3123-7. doi: 10.1002/j.1460-2075.1984.tb02268.x.
Unstable variants with increasing amounts of adenylate-deaminase (AMPD) have been stepwise recovered from Chinese hamster fibroblasts plated in selective medium containing increasing coformycin concentrations; several polypeptides accumulate in the variants in parallel to AMPD: they are no longer detectable in cells which reverted to the wild-type enzyme level. We report here the molecular cloning of cDNA sequences complementary to mRNAs coding for four such polypeptides. The plasmidic probes have been exploited to characterize their complementary mRNAs and to quantify the copies of these cognate genes in a variant and in two revertant clones. The results show that different mRNAs code for the four polypeptides; their accumulation is accounted for by amplification of their specific genes; these observations suggest that cells overproducing AMPD are characterized by the presence of amplification units comprising several expressed genes.
从接种于含有逐渐增加的助间型霉素浓度的选择培养基中的中国仓鼠成纤维细胞中，逐步回收了腺苷酸脱氨酶（AMPD）含量不断增加的不稳定变体；几种多肽与AMPD平行地在变体中积累：在回复到野生型酶水平的细胞中不再能检测到它们。我们在此报告与编码四种此类多肽的mRNA互补的cDNA序列的分子克隆。已利用质粒探针来表征其互补mRNA，并对一个变体和两个回复克隆中这些同源基因的拷贝进行定量。结果表明，不同的mRNA编码这四种多肽；它们的积累是由其特定基因的扩增引起的；这些观察结果表明，过量产生AMPD的细胞的特征是存在包含几个表达基因的扩增单元。
