MECHANISMS OF GLUCOSE SIGNAL TRANSDUCTION IN YEAST

描述(改编自申请人的摘要)：回复的能力 细胞外环境的变化是所有细胞的根本。这个 哺乳动物细胞的生长部分受细胞外细胞因子的控制 它们与完整的膜受体结合，进而调节细胞的活性 细胞内蛋白激酶。在酿酒酵母中，对 胞外葡萄糖浓度的变化有许多相似之处 哺乳动物细胞因子信号通路。编码的葡萄糖感受器蛋白 SNF3和RGT2是结合胞外葡萄糖的完整膜蛋白 并启动一条最终导致基因变化的信号通路 表情。Snf1丝氨酸/苏氨酸蛋白激酶在 信号葡萄糖限制，然而，葡萄糖通过的机制 传感器调节Snf1激酶的活性尚不清楚。 对一种名为std1的酵母蛋白的研究提供了一种可信和直接的 葡萄糖传感器和Snf1激酶之间的连接。双混合屏幕 对于与Std1相互作用的蛋白，确定了其C端亲水结构域 葡萄糖感受器，已被证明对葡萄糖至关重要的区域 发信号。早期的研究表明，std1与Snf1存在物理上的相互作用 而STD1基因剂量的增加抑制了Snf1激酶的突变 很复杂。更多数据证明STD1基因之间的遗传相互作用 (及其同系物MTH1)和编码影响葡萄糖传感器的基因 基因表达对细胞外葡萄糖水平变化的反应。 此外，Std1/MTH1和葡萄糖传感器之间的相互作用调节 Snf1激酶的活性。因为Std1可以与葡萄糖 传感器和Snf1激酶，这些数据支持这样一个模型，即Std1蛋白 作为膜受体和细胞外基质之间的信号中间体 细胞内蛋白激酶。 这些研究的长期目标是确定所有必需的蛋白质 用于葡萄糖信号转导，并确定其序列 相互作用及其调控机制。三个具体目标是 为本赠款期间提出的建议：1)评估 Std1和MTH1蛋白与葡萄糖传感器的相互作用 确定Snf1信号通路的其他组成部分；3) 识别与STd1和MTH1协同作用的其他蛋白质以调节 基因表达。

DESCRIPTION (adapted from the applicant's abstract): The ability to respond to changes in the extracellular environment is fundamental to all cells. The growth of mammalian cells is controlled in part by extracellular cytokines which bind to integral membrane receptors that in turn regulate the activity of intracellular protein kinases. In Saccharomyces cerevisiae, the response to changes in extracellular glucose concentration shares many similarities with mammalian cytokine signaling pathways. The glucose sensor proteins encoded by SNF3 and RGT2 are integral membrane proteins that bind extracellular glucose and initiate a signaling pathway that ultimately results in changes in gene expression. The Snf1 serine/threonine protein kinase plays an essential role in signaling glucose limitation, however the mechanism by which the glucose sensors regulate the activity of the Snf1 kinase has yet to be elucidated. Studies of a yeast protein called Std1 provide a plausible and direct connection between the glucose sensors and the Snf1 kinase. A two-hybrid screen for Std1 interacting proteins identified the C-terminal hydrophilic domains of the glucose sensors, domains that have been shown essential for glucose signaling. Earlier studies have shown that Std1 physically interacted with Snf1 and that increased gene dosage of STD1 suppressed a mutation in the Snf1 kinase complex. Additional data document genetic interactions between the STD1 gene (and its homologue MTH1) and the genes encoding the glucose sensors that affect gene expression in response to changes in extracellular glucose levels. Moreover, interactions between Std1/Mth1 and glucose sensors regulate the activity of the Snf1 kinase. Since Std1 can interact with both the glucose sensors and the Snf1 kinase, the data support a model whereby the Std1 protein acts as a signaling intermediate between the membrane receptors and the intracellular protein kinase. The long term goal of these studies is to identify all of the proteins required for glucose signal transduction and to determine the sequence of their interactions and their mechanism of regulation. Three specific aims are proposed for this grant period: 1) Assess the biological significance of the interaction between the Std1 and Mth1 proteins with the glucose sensors; 2) Identify additional components of the Snf1 kinase signaling pathway; 3) Identify additional proteins that act in concert with Std1 and Mth1 to regulate gene expression.