TARGETING AND ASSEMBLY OF THYLAKOID MEMBRANE PROTEINS

真核细胞具有许多膜结合的特征。 执行细胞必需的特殊功能的隔室。蛋白 靶向和转运系统维持这些物质的适当组成 车厢。蛋白质的错误靶向可能导致疾病。这方面的例子 是I细胞和高草酸尿症I，其中酶定位错误 车厢。我们研究的长期目标是了解分子 多种靶向和转位的基础和生化机制 系统。研究人员特别感兴趣的是 运输系统，以适应其底物的组装要求。 真核细胞由蛋白质输入系统和蛋白质输出系统组成。 后者来源于细菌细胞膜中存在的系统。在.期间 在过去的两年里，已经描述了两个新的出口系统。一种，称为 Delta pH系统，最早是在甲藻的囊泡膜上发现的 叶绿体，但似乎广泛存在于原核生物和 真核细胞器。德尔塔pH系统专门输送 与研究得很好的SecA/SecY系统并行地将蛋白质转移到管腔。这个 Delta pH系统的已识别组件不同于SEC的组件 系统。拟议的工作旨在确定存在的基础 这两个平行的系统，并阐明了三角洲 PH系统识别和运输它的蛋白质。第一个具体目标是 确定Delta pH系统是否可以运输折叠的蛋白质以及 Delta pH系统的底物在运输过程中需要折叠。这个 第二个具体目标是通过以下方法研究Delta pH体系的机理 描述了该途径的两个中间体。最后，他们提出了 将开发体外和体内测试的实验将检查 Delta pH体系各组分的功能及功能模体。 遗传学研究揭示了体内多种蛋白质的必要性 许多细胞膜中的运输系统。因此，结果是， 建议的研究将普遍适用于基本单元并与之相关 生物学和人类健康。

Eukaryotic cells are characterized by numerous membrane-bounded compartments that perform specialized functions essential for the cell. Protein targeting and translocation systems maintain the proper composition of these compartments. Mis-targeting of proteins can lead to disease. Examples of this are I-cell and hyperoxaluria I, where enzymes are localized to the wrong compartment. The long range goal of our research is to understand the molecular basis and biochemical mechanisms of a variety of targeting and translocation systems. The investigator's are particularly interested in the evolution of translocation systems to accommodate assembly requirements of their substrates. Eukaryotic cells consist of protein import systems and protein export systems. The latter derive from systems present in the bacterial cell membrane. During the last two years, two new export systems have been described. One, called the Delta pH system, was originally discovered in the thylakoied membrane of chloroplasts, but appears to be widely present in prokaryotes and also in eukaryotic organelles. The Delta pH system specifically transports a subset of proteins to the lumen in parallel with the well-studied SecA/SecY system. The identified components of the Delta pH system are unlike those of the Sec system. The proposed work aims to determine the basis for the existence of these two parallel systems and to elucidate the mechanisms by which the Delta pH system recognizes and transports it proteins. The first specific aim is to determine if the Delta pH system can transport folded proteins and if substrates of the Delta pH system need to be folded during transport. The second specific aim is to investigate the mechanism of the Delta pH system by characterizing two intermediates of the pathway. Finally, they propose experiments to develop in vitro and in vivo assays that will examine the functions and the functional motifs of components of the Delta pH system. Genetic studies have revealed the in vivo necessity of multiple protein transport systems in a number of cell membranes. Therefore, results of the proposed studies will be generally applicable and relevant to basic cell biology and human health.