Heterotrimeric G Protein Signaling in Arabidopsis

描述(由申请人提供)：在大多数后生动物中，不同 异三聚体G蛋白复合体将许多不同的上游信号偶联到 不同的下游效应因子，如腺苷环化酶、离子通道和 磷脂酶。然而，在拟南芥中，只有一个典型的 控制不同植物的异三聚体G蛋白复合体 回应。我们不知道这是如何实现的，也不知道是什么 受体激活这种G蛋白复合体。我的最新技术进步 小组使用增益和损失函数的方法来理解 拟南芥G蛋白亚基的功能将使我们能够确定 这种G蛋白复合体在各种信号通路中的分子作用。那里 是该项目的三个重点领域：根发育的生长素控制， 下胚轴发育；种子萌发的多信号调控。 具体地说，我们将：1.确定G蛋白突变体的生长素反应性 和过表达因子，并检测信号串扰控制种子 萌发，2.确定和表征遗传和物理交互作用 Galpha和Gbeta使用包括激活在内的基因外抑制物筛选 诱变和利用胞浆蛋白-蛋白相互作用分析，以及3.测试 基于反向遗传的一小部分候选GPCR的推测功能 接近了。总而言之，我们的目标是检验生长素利用 异三聚体G蛋白在信号转导中的作用这项工作还解决了一个 关于信号串扰机制的长期问题。因为，单曲 拟南芥异源三聚体G蛋白似乎是多种信号的中心 利用拟南芥的途径、遗传学研究可能揭示 信号集成，这很可能是普遍共享的。

DESCRIPTION (provided by applicant): In most metazoans, different heterotrimeric G protein complexes couple many different upstream signals to different downstream effectors such as adenyl cyclase, ion channels, and phospholipases. However, in Arabidopsis, there is only a single canonical heterotrimeric G protein complex that nonetheless controls different plant responses. We do not know how this is accomplished nor do we know what receptors activate this G protein complex. Recent technical advances from my group using both gain- and loss-of-function approaches to understand the function of Arabidopsis G protein subunits will enable us to determine the molecular role of this G protein complex in various signaling pathways. There are three focus areas for this project: auxin control of root development, hypocotyl development; and multi-signal control of seed germination. Specifically, we will: 1. determine auxin responsiveness of G protein mutants and overexpressors and examine the signal cross-talk controlling seed germination, 2. identify and characterize genetic and physical interactors of Galpha and Gbeta using extragenic suppressor screens including activation mutagenesis and using cytosolic protein-protein interaction assays, and 3. test putative functions of a small set of candidate GPCRs using reverse genetic approaches. In summary, the goal is to test the hypothesis that auxin utilizes heterotrimeric G proteins in signal transduction. This work also addresses a longstanding problem on the mechanism of signal cross-talk. Because, the single Arabidopsis heterotrimeric G protein appears to be central to multiple signal pathways, genetic studies using Arabidopsis may reveal the core mechanism of signal integration, which is likely to be shared universally.