Chevallier-Multon M C, Schweighoffer F, Barlat I, Baudouy N, Fath I, Duchesne M, Tocqué B
Molecular Oncology Laboratory, CRVA-IBV, Rhône-Poulenc Rorer, Vitry sur Seine, France.
J Biol Chem. 1993 May 25;268(15):11113-8.
The best characterized yeast guanine nucleotide releasing factor is CDC25, which acts on RAS and thereby stimulates cAMP production in Saccharomyces cerevisiae. In order to determine if CDC25 could be a specific GDP-GTP releasing factor for the mammalian proteins Ha-ras, Ki-ras, and N-ras, its functions were studied both in vitro and in NIH3T3 cells. The 561 amino acid composing the C-terminal domain of CDC25 (CDC25 C-domain) released guanine nucleotides (both GDP and GTP) from Ha-, Ki-, and N-ras but not from Rap1A, Rab5, and Rab11. CDC25 acted on oncogenically activated Ha-ras even if the last 23 amino acids (167-189) of the Ras proteins were not present. CDC25 transformed NIH3T3 cells; its transforming capacity was enhanced by overexpression of wild-type Ha-ras. CDC25 C-domain probably exerts its effects through the activation of cellular Ras proteins. These data suggest that the CDC25 C-domain can function as an upstream activator of Ras proteins in a heterologous system and therefore could be a useful tool to study the regulation of Ras activation by growth factor receptors.
研究得最清楚的酵母鸟嘌呤核苷酸释放因子是CDC25，它作用于RAS，从而刺激酿酒酵母中的cAMP产生。为了确定CDC25是否可能是哺乳动物蛋白Ha-ras、Ki-ras和N-ras的特异性GDP-GTP释放因子，对其在体外和NIH3T3细胞中的功能进行了研究。构成CDC25 C端结构域（CDC25 C结构域）的561个氨基酸从Ha-ras、Ki-ras和N-ras释放鸟嘌呤核苷酸（GDP和GTP），但不从Rap1A、Rab5和Rab11释放。即使Ras蛋白的最后23个氨基酸（167-189）不存在，CDC25也作用于致癌激活的Ha-ras。CDC25转化NIH3T3细胞；野生型Ha-ras的过表达增强了其转化能力。CDC25 C结构域可能通过激活细胞Ras蛋白发挥其作用。这些数据表明，CDC25 C结构域可以在异源系统中作为Ras蛋白的上游激活剂发挥作用，因此可能是研究生长因子受体对Ras激活调控的有用工具。
