Dynamics and Structure of Arabinogalactan-Proteins at the Plasma Membrane-Cell Wall Interface in Plants

阿拉伯半乳聚糖蛋白（AGPs）和其他 糖缀合物在质膜之间的界面， 玫瑰细胞的细胞壁表明，这些分子作为 在这两种不同的表面之间的介导剂 结构. 这一假设将在全细胞上进行测试， 模型系统通过分析扰动的AGP对 质膜成分的横向扩散和线性扩散 质膜和细胞壁之间的运动。 特性 这些类型的运动将被确定为函数 膨胀或施加压力。 AGP的扰动将包括 聚集、酶促裂解和改变的合成。 等 表征将提供有关影响的进一步信息 对膜动力学的影响。 酶能够 在活原生质体上切割质膜AGP将是进一步的 纯化并阐明其作用模式。 分析 质膜AGPs和分子的生化结构， 在分离过程中与质膜AGP共纯化也将是 进行。 质膜AGP的结构分析将 包括测定糖基键组成，主要 异头构型和氨基末端序列。的 生物化学研究将提供重要的信息， 了解AGPs作为介导剂或/和作为 特定的识别分子。 植物的细胞壁是复杂的细胞外基质 含有蛋白质和多糖成分的结构， 其详细的组织结构在很大程度上是未知的。 的结果 细胞的高水压状态称为膨压， 膜必须紧紧贴壁约7 大气压力。 然而，膜的组成部分 必须自由地进行快速的横向扩散，即使 紧贴在墙上 这在细胞内尤其如此。 增长 已经发现了许多蛋白质连接的糖缀合物 在质膜中，其中的碳水化合物部分是 在细胞外部并在膜和壁之间延伸。 其中一些类似于动物细胞的蛋白聚糖 膜。 它们的功能是完全未知的。 这 项目将探讨一个小组的功能和结构方面 这些糖复合物，阿拉伯半乳聚糖，假设 考虑到阿拉伯半乳聚糖可以作为物理介质 或植物细胞膜和细胞壁之间的缓冲层。

The abundance of arabinogalactan-proteins (AGPs) and other glycoconjugates at the interface between the plasma membrane and the cell wall of rose cells suggests that these molecules serve as mediating agents between the surfaces of these two distinct structures. This hypothesis will be tested on whole cells and model systems by analyzing the effect of perturbations of AGPs on both lateral diffusion of plasma membrane components and on linear motion between the plasma membrane and cell wall. Characteristics of these types of motions will be determined as a function of turgor or applied pressure. Perturbations of AGPs will include aggregation, enzymatic cleavage, and altered synthesis. Such characterization will provide further information on the effects of both turgor and AGPs on membrane dynamics. Enzymes capable of cleaving plasma membrane AGPs on live protoplasts will be further purified and their mode of action elucidated. Analysis of the biochemical structure of plasma membrane AGPs and molecules that copurify with plasma membrane AGPs during isolation will also be conducted. Structural analysis of plasma membrane AGPs will include determination of glycosyl linkage composition, predominant anomeric configurations, and amino terminal sequence. The biochemical studies will provide important information towards understanding the role of AGPs as mediating agents or/and as specific recognition molecules during development. The cell walls of plants are complex extracellular matrix structures containing protein and polysaccharide components, the detailed organization of which is largely unknown. As a result of the cellular high water pressure state known as turgor, the plasma membrane must be tightly appressed to the wall by about 7 atmospheres of pressure. However, the components of the membrane must be free to undergo rapid lateral diffusion, even while appressed against the wall. This is particularly true during cell growth. A number of protein-linked glycoconjugates have been found in the plasma membrane, the carbohydrate portion of which is external to the cell and extends between the membrane and the wall. Some of these are analogous to proteoglycans of animal cell membranes. The functions of these are totally unknown. This project will explore functional and structural aspects of one group of these glycoconjugates, the arabinogalactans, with the hypothesis in mind that the arabinogalactans may serve as physical mediators or cushions between the membrane and the wall of plant cells.