Structure and Function of a Novel, Modular Arabinogalactan-Protein from Tomato

9727757;PI—Showalter arabinogalacan -proteins （AGPs）是一类广泛分布于植物体内的富含羟基脯氨酸的糖蛋白。agp存在于细胞间隙、细胞壁和质膜中，在生长发育中起重要作用。这一建议着重于推测的质膜AGP，即从番茄DNA克隆中推断出的证明发育和器官特异性调控的LeAGP-1。这些克隆预测了一种新型的模块化AGP，由n端信号肽、中心经典AGP结构域夹在一个基本亚结构域和c端推定的跨膜结构域组成。我们的工作假设是，leagp -1代表了一种质膜AGP，它的功能是建立连接并介导细胞壁的粘附，类似于动物细胞的粘附分子。pi将测试这些假设，并通过以下方式解决legp -1的结构和功能：1)从番茄细胞培养中分离和生化表征LeAGP-1，为功能表征提供结构信息和材料；2)在培养细胞、茎、花和胞浆化细胞中免疫定位LeAGP-1，展示膜和壁之间的粘附区；3)在分子水平（分子间交联测试）和整株水平（转基因植物中LeAGP-1反义抑制/义共抑制）上对其进行功能表征。

9727757; PI -- Showalter Arabinogalactan-proteins (AGPs) are a family of hydroxyproline-richglycoproteins which are widely distributed in plants. AGPs are found inintercellular spaces, cell walls, and plasma membranes and implicated toplay important roles in growth and development. This proposal focuses on aputative plasma membrane AGP, LeAGP-1, deduced from tomato DNA clones whichdemonstrate developmental and organ-specific regulation. The clonespredict a novel, modular AGP comprised of an N-terminal signal peptide, acentral classical AGP domain sandwiching a basic subdomain, and C-terminalputative transmembrane domain. Our working hypotheses are that LeAGP-1represents a plasma membrane AGP and that it functions in establishingconnections and mediating adhesion to the cell wall, analogous to animalcell adhesion molecules. The PIs will test these hypotheses and addressstructure and function of LeAGP-1 by: 1) isolating and biochemicallycharacterizing LeAGP-1 from tomato cell cultures to provide structuralinformation and material for functional characterization, 2)immunolocalizing LeAGP-1 in cultured cells, stems, and flowers and inplasmolyzed cells demonstrating zones of adhesion between the membrane andwall, and 3) functionally characterizing LeAGP-1 at the molecular level(tests for intermolecular crosslinking) and whole plant level (LeAGP-1antisense suppression/sense cosuppression in transgenic plants).