Der C J, Finkel T, Cooper G M
Cell. 1986 Jan 17;44(1):167-76. doi: 10.1016/0092-8674(86)90495-2.
Using site-directed mutagenesis, we have introduced mutations encoding 17 different amino acids at codon 61 of the human rasH gene. Fifteen of these substitutions increased rasH transforming activity. The remaining two mutants, encoding proline and glutamic acid, displayed transforming activities similar to the normal gene. Overall, these mutants vary over 1000-fold in transforming potency. Increased levels of p21 expression were required for transformation by weakly transforming mutants. The mutant proteins were unaltered in guanine nucleotide binding properties. However, all 17 different mutant proteins displayed equivalently reduced rates of GTP hydrolysis, 8- to 10-fold lower than the normal protein. There was no quantitative correlation between reduction in GTPase activity and transformation, indicating that reduced GTP hydrolysis is not sufficient to activate ras transforming potential.
利用定点诱变技术，我们在人rasH基因的第61密码子处引入了编码17种不同氨基酸的突变。其中15种替换增加了rasH的转化活性。其余两个编码脯氨酸和谷氨酸的突变体，其转化活性与正常基因相似。总体而言，这些突变体的转化能力相差超过1000倍。弱转化突变体进行转化需要增加p21表达水平。突变蛋白的鸟嘌呤核苷酸结合特性未改变。然而，所有17种不同的突变蛋白的GTP水解速率均同等程度降低，比正常蛋白低8至10倍。GTP酶活性降低与转化之间不存在定量相关性，这表明GTP水解减少不足以激活ras的转化潜能。
