已有研究证明ROP6-RIC1信号途径促进了嵌合生长的拟南芥叶片表皮细胞凹陷区周质微管有序排列成横向微管列阵，调控细胞的扩张性生长和形态建成。本项目通过遗传筛选和图位克隆方法鉴定到了一个植物小G蛋白ROP6-RIC1信号途径的新成员ARK2。ARK2基因编码了一个植物特异的含有犰狳重复序列的动蛋白相关蛋白(armadillo repeat-containing kinesin-related protein)。遗传学证据表明，ARK2在ROP6-RIC1信号途径的下游发挥作用并且可以影响细胞内微管的排列方式。体外生化分析和双分子荧光互作实验证明，ARK2可以和RIC1在体外和细胞内直接结合。本项目拟分析ARK2是如何通过与RIC1的结合，增强了细胞中ARK2的微管亲和性和马达活性，最终有利于微管形成有序排列的横向微管列阵，进而影响了表皮细胞扩张性生长的调控机制。

Previous studies have shown that ROP6-RIC1 signaling pathway promotes the formation of transverse microtubules to restrict lateral cell expansion in Arabidopsis pavement cells. Our genetic screens identified the armadillo repeat-containing kinesin-related protein 2, ARK2, as a downstream component of the ROP6-RIC1 signaling pathway. The ark2 phenotype is dependent on the function of microtubules. In vivo and in vitro studies showed that RIC1 physically interacted with ARK2. The project intends to analyze the role for RIC1 in promoting the microtubule-binding ability and microtubule-stimulated ATPase of ARK2, so as to contribute to well-ordered transverse cortical microtubules and restrict radial cell expansion. The research findings uncovered not only an explicit regulatory mechanism underpinning the regulation of microtubules alignment and ordering by ROP6-RIC1 pathway, but also a signaling pathway that regulates the plant-specific kinesin with microtubule binding and microtubule motor activity.