Anderson David J, Botella José R
Plant Genetic Engineering Laboratory, School of Integrative Biology, The University of Queensland, St. Lucia, QLD 4072, Australia.
Plant Cell Rep. 2007 Sep;26(9):1469-80. doi: 10.1007/s00299-007-0356-1. Epub 2007 May 10.
Heterotrimeric GTP-binding proteins (G-proteins), consisting of Galpha, Gbeta, and Ggamma subunits, function as molecular switches in many eukaryotic signal transduction pathways. In contrast to many eukaryotes, plants contain very few G-protein subunit isoforms that mediate a diverse array of signalling functions. We investigated the contribution of cell type-specific expression and subcellular localization to this multifunctional signalling capacity for the Arabidopsis thaliana Gbeta subunit, AGB1. Analysis of AGB1 promoter::beta-glucuronidase (GUS) fusions in germinating seeds, seedlings, and flowering plants revealed that AGB1 is widely expressed throughout development in a complex manner. As well as demonstrating similarities to existing Arabidopsis G-protein subunit expression data, several features of the AGB1 expression pattern align closely with known or proposed G-protein functions. A C-terminal AGB1-green fluorescent protein (GFP) fusion was localized at the plasma membrane and in the nucleus of leaf epidermal cells, trichomes and root cells, supporting previous evidence that plant G-protein functionality relies on subcellular compartmentalization.
异源三聚体GTP结合蛋白（G蛋白）由Gα、Gβ和Gγ亚基组成，在许多真核生物信号转导途径中起分子开关的作用。与许多真核生物不同，植物中介导多种信号功能的G蛋白亚基异构体很少。我们研究了细胞类型特异性表达和亚细胞定位对拟南芥Gβ亚基AGB1这种多功能信号传导能力的贡献。对萌发种子、幼苗和开花植物中AGB1启动子::β-葡萄糖醛酸酶（GUS）融合体的分析表明，AGB1在整个发育过程中以复杂的方式广泛表达。除了显示出与现有的拟南芥G蛋白亚基表达数据相似外，AGB1表达模式的几个特征与已知或推测的G蛋白功能密切相关。C末端AGB1-绿色荧光蛋白（GFP）融合体定位于叶表皮细胞、毛状体和根细胞的质膜和细胞核中，支持了先前关于植物G蛋白功能依赖于亚细胞区室化的证据。
