Analysis of G Protein Functions in Arabidopsis

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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. ***