Regulation of the actin cytoskeleton by ROPs in plants

Ras超家族的鸟嘌呤核苷酸结合蛋白参与了许多信号转导和转运过程。Rho蛋白亚家族在许多不同的生物系统中调节肌动蛋白细胞骨架的重组。这些途径和机制已经在哺乳动物和酵母细胞中得到了深入的研究。已经证明，Rho蛋白通过与效应器结合来发挥作用，效应器被定义为与GNBP的激活(GTP结合)状态结合的蛋白质。这些效应器通过直接与肌动蛋白踏车系统各组成部分相互作用或调节其活性来介导Rho蛋白的信号转导级联反应。Rho同源蛋白(ROP)已经在植物中被发现(在拟南芥中有11个)，但几乎不知道它们被GEF和GAP调控。对植物中肌动蛋白细胞骨架的调控更是知之甚少，因为到目前为止还没有从植物中分离出常见效应器的同源物。在这里，我们打算克隆、表征和分析从激活ROPs到其对肌动蛋白细胞骨架的调控的生化和结构上的途径。

Guanine nucleotide binding proteins of the Ras superfamily are involved in many signal transduction and transport processes. The subfamily of Rho proteins regulates reorganization of the actin cytoskeleton in many different biological systems. These pathways and mechanisms have been intensively studied in mammalian and yeast cells. It has been shown that Rho proteins act by binding to effectors, which are defined as proteins binding to the activated (GTP-bound) state of the GNBP. These effectors mediate the signal transduction cascade of Rho proteins by directly interacting with or regulating the activity of components of the actin treadmilling system. Rho homologous proteins (Rops) have been identified in plants (11 in Arabidopsis thaliana) but almost nothing is known of their regulation by GEFs and GAPs. Even less is known about the regulation of the actin cytoskeleton in plants since no homologues of the common effectors have so far been isolated from plants. Here we intend to clone, characterize and analyse biochemically and structurally the pathway leading from activation of Rops to its regulation of the actin cytoskeleton.