The ras1 function of Schizosaccharomyces pombe mediates pheromone‐induced transcription.
The ras1 function of Schizosaccharomyces pombe mediates pheromone‐induced transcription.
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粟酒裂殖酵母的 ras1 功能介导信息素诱导的转录。
作者：
Olaf Nielsen;John Davey;R. Egel
ras1+功能的丧失使得裂殖酵母细胞无法响应交配信息素而发生形态变化，而携带ras1激活突变的细胞则具有高反应性。这表明 ras1 基因产物在交配信息素信号转导中发挥作用。使用部分纯化的 M 因子，我们证明了控制进入减数分裂的 mat1-Pm 基因是响应信息素信号而转录的。 ras1 基因或 ste6（Ras 蛋白 GDP/GTP 交换因子的裂殖酵母同源物）突变的菌株无法响应 M 因子诱导 mat1-Pm 转录。此外，激活的 ras1val17 突变体表现出更强的 mat1-Pm 转录本诱导作用。然而，转录仍然依赖于氮剥夺以及信息素的存在，这表明单独激活 Ras1 蛋白并不能替代任何这些信号。 pat1-114 突变体绕过 ras1/ste6 检查点，表明 ras1 的激活有助于 pat1 蛋白激酶的失活。
Loss of ras1+ function renders fission yeast cells unable to undergo morphological changes in response to mating pheromones, whereas cells carrying activated mutations in ras1 are hyper‐responsive. This has led to the suggestion that the ras1 gene product plays a role in mating pheromone signal transduction. Using partially purified M factor we demonstrate that the mat1‐Pm gene, which controls entry into meiosis, is transcribed in response to a pheromone signal. Strains mutated in the ras1 gene or in ste6, the fission yeast homologue of Ras protein GDP/GTP exchange factor, are unable to induce transcription of mat1‐Pm in response to M factor. Furthermore, an activated ras1val17 mutant exhibits a stronger induction of the mat1‐Pm transcript. However, transcription still depends on nitrogen deprivation as well as on the presence of pheromone, showing that activation of the Ras1 protein alone does not substitute for any of these signals. The pat1‐114 mutant bypasses the ras1/ste6 checkpoint, suggesting that activation of ras1 contributes to inactivation of the pat1 protein kinase.