小背景：The activity of Rho of plant (ROP) GTPases is regulated by the opposing action of guanine nucleotide-exchange factors (GEFs) and GTPase-activating proteins (GAPs). 

提出问题：Whereas plant-specific ROPGEFs have been shown to be embedded in higher-level regulatory mechanisms involving membrane-bound receptor-like kinases, the regulation of GAPs has remained enigmatic.

主要发现：Here, we show that three Arabidopsis ARMADILLO REPEAT ONLY (ARO) proteins are essential for the stabilization of growth sites in root hair cells and trichomes.

结果：AROs interact with ROP1 enhancer GAPs (RENGAPs) and bind to the plasma membrane via a conserved polybasic region at the ARO amino terminus.

结论：The ectopic spreading of ROP2 in aro2/3/4 mutant root hair cells and the preferential interaction of AROs with active ROPs and anionic phospholipids suggests that AROs recruit RENGAPs into complexes with ROPs to confine ROP signallingto distinct membrane regions.