Howell N, Bantel A, Huang P
Somatic Cell Genet. 1983 Nov;9(6):721-43. doi: 10.1007/BF01539476.
Mouse LA9 cell lines were selected for increased resistance to either HQNO or myxothiazol, inhibitors of electron transport which bind to the mitochondrial cytochrome b protein. Two phenotypically distinguishable HQNO-resistant mutants were recovered while the myxothiazol-resistant isolates had a common phenotype. All three mutant phenotypes were transmitted cytoplasmically in cybrid crosses. Biochemical studies further established that for all three mutant types, resistance at the cellular level was paralleled by an increase in inhibitor resistance of mitochondrial succinate-cytochrome c oxidoreductase, the respiratory complex containing cytochrome b. As with the previously described mitochondrial antimycin-resistant mutant, the initial biochemical and genetic studies indicated that these mutations occur within the mitochondrial cytochrome b gene. This conclusion was strongly supported by the results of mtDNA restriction fragment analyses in which it was found that one HQNO-resistant mutant had undergone a small insertion or duplication in the apocytochrome b gene. Finally, all four mitochondrial cytochrome b mutants have been analyzed in both cell plating studies and succinate-cytochrome c oxidoreductase assays to determine the pattern of cross-resistance to inhibitors of cytochrome b other than the one used for selection.
选择小鼠LA9细胞系以增强对 HQNO 或粘噻唑的抗性，这两种电子传递抑制剂与线粒体细胞色素 b 蛋白结合。回收了两个表型可区分的 HQNO 抗性突变体，而粘噻唑抗性分离株具有共同的表型。在细胞杂交中，所有三种突变体表型都是通过细胞质传递的。生化研究进一步证实，对于所有三种突变类型，细胞水平的抗性与线粒体琥珀酸 - 细胞色素 c 氧化还原酶（包含细胞色素 b 的呼吸复合体）对抑制剂抗性的增加平行。与先前描述的线粒体抗霉素抗性突变体一样，最初的生化和遗传研究表明这些突变发生在线粒体细胞色素 b 基因内。线粒体 DNA 限制性片段分析结果有力地支持了这一结论，其中发现一个 HQNO 抗性突变体在脱辅基细胞色素 b 基因中发生了小的插入或重复。最后，对所有四个线粒体细胞色素 b 突变体进行了细胞铺板研究和琥珀酸 - 细胞色素 c 氧化还原酶测定，以确定对用于选择之外的细胞色素 b 抑制剂的交叉抗性模式。
