Analysis of G Protein Functions in Arabidopsis

g蛋白在真核生物受体介导的信号传导过程中发挥重要作用。关于植物信号转导过程的分子机制知之甚少，其中各种激素和环境信号影响植物的发育、成熟和衰老。生化分析表明，g蛋白也参与了植物的信号转导过程。在先前的授权期间，从拟南芥中分离到GPA1基因（异源三聚体G蛋白的α亚基编码基因），并对其进行了测序和表达研究。由于该基因在大多数器官发育过程中均有表达，且在快速分裂细胞、年轻器官细胞和营养传递细胞中表达水平较高，因此认为该基因的产物是细胞分裂所必需的。对转基因植物的研究进一步表明g蛋白的α亚基在发育过程中调控分化的作用。在本提案中，实验描述了进一步测试g蛋白在转基因植物细胞调控中的作用，鉴定和表征与GPA1基因相互作用的蛋白，结束编码这些蛋白的基因的分离。这些实验是这项工作的合理延续，如果成功，将提供有关GPA1在植物细胞中的功能的详细信息。马博士的实验室过去已经成功地研究了g蛋白在植物细胞发育中的作用，包括GPA1基因在发育植物中的空间和时间表达，在含有各种GPA1基因构建体的转基因植物中，基因产物在细胞中的免疫定位和GPA1基因的定位。在目前的研究中，他将重点分析转基因植物和组织培养中GPA1基因的功能，在体外分析GPA1的功能和相互作用蛋白，并将分离编码GPA1介导的信号通路成分的基因。他将与其他人合作进行其中一些实验。这些研究将极大地增加我们对植物信号反应的理解。PI的实验室非常擅长生产这项工作成功所需的遗传物质和工具。马博士显然是信号转导领域的新兴领导者。＊＊＊

9316048 Ma G-proteins play important roles in the receptor-mediated signaling processes in eukaryotic organisms. Little is known about the molecular mechanisms of signal transduction processes in plants, where a variety of hormonal and environmental signals affect development, maturation and senescence. Biochemical analyses suggested that G-proteins are also involved in the signal transduction processes in plants. During the previous granting period the GPA1 gene (the alpha subunit encoding gene of the heterotrimeric G protein) was isolated from Arabidopsis thaliana, sequenced and its expression investigated. since the gene was expressed in most organs during development, and its level of expression was high in rapidly dividing cells, in cells of young organs and nutrient transmitting cells, it was suggested that the product of this gene is required for cell division. Investigations with transgenic plants further suggested the role of the alpha subunit of the G-protein in the regulation of differentiation during development. In the present proposal experiments are described to further test the role of the G-protein in cellular regulation with transgenic plants, on identification and characterization of proteins that interact with the GPA1 gene, end of the isolation of the genes encoding these proteins. These experiments are the logical continuation of the work, and if successful, will provide detailed information about the function of GPA1 in plant cells. %%% Dr. Ma's laboratory has successfully studied in the past the role of G-protein in the development of plant cells, including the spatial and temporal expression of the GPA1 gene in developing plants, in transgenic plants containing various constructs of the GPA1 gene, immunolocalization of the gene product in cells and mapping of the GPA1 gene. In the present study he will focus on the analysis of GPA1 gene function in transgenic plants and in tissue cultures, on the in vitro analysis of the GPA1 function and interacting proteins, and will isolate the genes which encode components of the GPA1 mediated signaling pathway. He will carry out some of these experiments in collaboration with others. These studies will add enormously to our understanding of plant signaling responses. The PI's laboratory is very good at producing the genetic materials and tools that are needed for success in this work. Dr. Ma is clearly an emerging leader in the signal transduction area. ***