Verner K, Lemire B D
Biocenter, University of Basel, Switzerland.
EMBO J. 1989 May;8(5):1491-5. doi: 10.1002/j.1460-2075.1989.tb03533.x.
The first seven residues of the yeast cytochrome oxidase subunit IV presequence are insufficient to target attached mouse dihydrofolate reductase into isolated yeast mitochondria. However, the targeting function of this truncated presequence can be restored by presenting the fusion protein to isolated mitochondria either as nascent, unfolded chains, or as full-length chains whose dihydrofolate reductase moiety had been destabilized either by urea treatment or by point mutations. The targeting efficiency of a mitochondrial presequence can thus be strongly influenced by the conformation of the attached 'passenger protein'. These results also underscore the difficulty of defining a 'minimal' mitochondrial targeting signal.
酵母细胞色素氧化酶亚基IV前序列的前七个残基不足以将附着的小鼠二氢叶酸还原酶靶向到分离的酵母线粒体中。然而，通过将融合蛋白以新生的、未折叠的链的形式，或者以其二氢叶酸还原酶部分已通过尿素处理或点突变而不稳定的全长链的形式呈现给分离的线粒体，可以恢复这种截短前序列的靶向功能。因此，线粒体前序列的靶向效率会受到附着的“乘客蛋白”构象的强烈影响。这些结果也凸显了定义“最小”线粒体靶向信号的困难。
