A Cell Wall Associated, Receptor Like Kinase

Iohorn 9603703技术我们已经鉴定出一个拟南芥蛋白家族，命名为WAKS，与细胞壁密切相关，具有细胞质激动域。每个家族成员的细胞壁结合、胞外结构域包含几个表皮生长因子(EGF)重复序列。然而，WAKS在细胞外域方面有所不同。在不同的100个氨基酸片段中，一个WAK与Tenascin有54%的同源性(理想间距)。在另一种情况下，与Neuresin同一性，在另一种情况下，与Extensin同一性。WAK家族在拟南芥的所有营养组织中都有表达，在其他被子植物中也有亲缘关系。基于免疫电子显微镜和生化分析，WAKS在细胞壁和细胞质之间提供了物理上的连续体。因为该激酶是细胞质的，所以它也有可能将信号从细胞壁传递到细胞质。事实上，我们发现至少有一个Wak与细胞质2C蛋白磷酸酶相互作用，这可能是转导途径的第一步。未来的实验将集中在每个家族成员的基因组组织和特异性表达，以及它们与彼此和细胞质蛋白的相互作用。我们已经分离到一个与胚胎致命表型紧密相关的WAK基因座的T-DNA中断，我们计划利用这个突变背景来分析WAKS的功能结构域。此外，显性负Wak突变的表达也表明该家族对生存是必不可少的，遗传筛选将用于识别相互作用的蛋白质。影响植物细胞的非技术外在信号首先与细胞周围的细胞壁相互作用。这些外部信号中的许多都会导致植物生理和形态的明显变化。这些信号中的大多数检测到的位置尚不清楚。科霍恩博士发现了一类信号蛋白(细胞壁相关蛋白或WAK)，它们与细胞表面直接相邻的细胞壁内表面相关。凭借这一奖项，科霍恩博士将确定编码WAK的基因的特征，并研究WAK如何与其他蛋白质相互作用，创建一个耦合的级联，其中WAK感知的信号被传输到细胞中，从而发挥生理效应。***

Iohorn 9603703 Technical We have identified a family of Arabidopsis thaliana proteins, designated Waks for Wall Associated Kinase, that are tightly associated with the cell wall, and that have cytoplasmic kinase domains. The cell wall bound, extracytoplasmic domain of each family member contains several Epidermal Growth Factor (EGF) repeats. Waks differ, however, in the extracellular domain . In different 100 amino acid blocks one Wak has 54% identity (perfect spacings) to tenascin. In another there is identity with a neurexin and in another there identity with extensin. The Wak family is expressed in all vegetative tissues of Arabidopsis, and has relatives in other Angiosperms. Based on immunoelectron microscopy and biochemical analysis, Waks provides a physical continuum between the cell wall and the cytoplasm. Since the kinase is cytoplasmic it also has the potential to mediate signals to the cytoplasm from the cell wall. Indeed, we find that at least one Wak interacts with a cytoplasmic type 2C protein phosphatase that is likely the first step in the transduction pathway. Future experiments will focus on the genomic organization and specific expression of each family member, and their interaction with each other and cytoplasmic proteins. We have isolated a T-DNA disruption of the Wak locus that is tightly linked to an embryonic lethal phenotype, and we plan to use this mutant background to assay functional domains of the Waks. Moreover, expression of dominant negative Wak mutations also show that the family is essential for viability, and genetic screens will be used to identify interacting proteins. Non-Technical Extrinsic signals impinging upon plant cells first interact with the cell wall that surrounds the cell. Many of these extrinsic signals induce overt alterations in a plant's physiology and morphology. The site of detection of these most of these signals is unknown. Dr. Kohorn has discovered a class of signaling proteins (cell-wall associated kinase or Wak) that app ear to be associated with the inner surface of the cell wall directly adjacent to the cell surface. With this award Dr. Kohorn will characterize the genes encoding Wak and to examine how Wak interacts with other proteins to create a coupled cascade where signals perceived by Wak are transmitted into the cell to exert physiological effects. ***