Jones S, Vignais M L, Broach J R
Department of Molecular Biology, Princeton University, New Jersey 08544.
Mol Cell Biol. 1991 May;11(5):2641-6. doi: 10.1128/mcb.11.5.2641-2646.1991.
The product of the CDC25 gene of Saccharomyces cerevisiae, in its capacity as an activator of the RAS/cyclic AMP pathway, is required for initiation of the cell cycle. In this report, we provide an identification of Cdc25p, the product of the CDC25 gene, and evidence that it promotes exchange of guanine nucleotides bound to Ras in vitro. Extracts of strains containing high levels of Cdc25p catalyze both removal of GDP from and the concurrent binding of GTP to Ras. This same activity is also obtained with an immunopurified Cdc25p-beta-galactosidase fusion protein, suggesting that Cdc25p participates directly in the exchange reaction. This biochemical activity is consistent with previous genetic analysis of CDC25 function.
酿酒酵母CDC25基因的产物作为RAS/环磷酸腺苷途径的激活剂，是细胞周期起始所必需的。在本报告中，我们鉴定了CDC25基因的产物Cdc25p，并提供证据表明它在体外促进与Ras结合的鸟嘌呤核苷酸的交换。含有高水平Cdc25p的菌株提取物催化从Ras上除去GDP并同时将GTP结合到Ras上。用免疫纯化的Cdc25p-β-半乳糖苷酶融合蛋白也可获得相同的活性，这表明Cdc25p直接参与交换反应。这种生化活性与先前对CDC25功能的遗传分析一致。
