Scolnick E M, Papageorge A G, Shih T Y
Proc Natl Acad Sci U S A. 1979 Oct;76(10):5355-9. doi: 10.1073/pnas.76.10.5355.
We have recently identified a 21,000-dalton protein, p21, coded for by Kirsten or Harvey murine sarcoma virus. On the basis of the results obtained with the p21 of a mutant of Kirsten sarcoma virus, temperature sensitive for the maintenance of transformation, we concluded that the p21 was required for the maintenance of transformation induced by either virus. We report herein that when extracts from cells transformed by Kirsten or Harvey sarcoma virus are incubated with [(3)H]GDP or [alpha-(32)P]GTP, picomole quantities of guanine nucleotide can be immunoprecipitated with antisera that contain antibodies to the p21. Previously we have shown that the immunoprecipitability of [(35)S]methionine-labeled p21 of the temperature-sensitive mutant of Kirsten sarcoma virus is thermolabile. The binding of guanine nucleotide is shown herein also to be thermolabile in extracts of cells transformed by the same mutant. However, the immunoprecipitability of the [(35)S]methionine-labeled p21 in such extracts of the temperature-sensitive mutant can be preserved if the extracts containing labeled p21 are incubated with added GDP or GTP prior to heating. The results suggest an interaction between p21 and certain guanine nucleotides, and the possible roles of guanine nucleotides and p21 in the maintenance of transformation are discussed.
我们最近鉴定出一种由 Kirsten 或 Harvey 鼠肉瘤病毒编码的 21,000 道尔顿蛋白质 p21。基于对 Kirsten 肉瘤病毒突变体的 p21 所获得的结果（该突变体对维持转化具有温度敏感性），我们得出结论，p21 是维持由任一病毒诱导的转化所必需的。我们在此报告，当用 Kirsten 或 Harvey 肉瘤病毒转化的细胞提取物与[³H]GDP 或[α - ³²P]GTP 一起孵育时，皮摩尔量的鸟嘌呤核苷酸可以用含有针对 p21 的抗体的抗血清进行免疫沉淀。此前我们已表明，Kirsten 肉瘤病毒温度敏感突变体的[³⁵S]甲硫氨酸标记的 p21 的免疫沉淀性是热不稳定的。本文还表明，在由同一突变体转化的细胞提取物中，鸟嘌呤核苷酸的结合也是热不稳定的。然而，如果在加热之前将含有标记 p21 的提取物与添加的 GDP 或 GTP 一起孵育，则温度敏感突变体的此类提取物中[³⁵S]甲硫氨酸标记的 p21 的免疫沉淀性可以得到保留。这些结果表明 p21 与某些鸟嘌呤核苷酸之间存在相互作用，并讨论了鸟嘌呤核苷酸和 p21 在维持转化中的可能作用。
