Xu Jian, Scheres Ben
Department of Molecular Genetics, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands.
Curr Opin Plant Biol. 2005 Dec;8(6):613-8. doi: 10.1016/j.pbi.2005.09.003. Epub 2005 Sep 22.
Cell polarity plays an important role in plant development, but the mechanisms that first establish polarity cues remain obscure. By contrast, a flurry of information has recently emerged on the elaboration of cell shape from such unknown initial cell-polarity cues. Recent studies suggest that Rho-related GTPases in plants (ROPs), and their effector targets among the ROP-interactive CRIB motif-containing proteins (RICs), mediate two antagonistic pathways that have opposing action on cell polarization. ROP proteins appear to interact directly with upstream regulators of the ARP2/3 complex, which are conserved modulators of the actin cytoskeleton. ROP function is dependent on the class 1 ADP-ribosylation factors (ARFs), which are core components of the vesicle transport machinery that are also involved in the polar localization of PIN-FORMED (PIN) family auxin efflux facilitators.
细胞极性在植物发育中起着重要作用，但最初建立极性线索的机制仍不清楚。相比之下，最近涌现出了大量关于从这种未知的初始细胞极性线索细化细胞形状的信息。最近的研究表明，植物中的Rho相关GTP酶（ROPs）及其在含ROP相互作用CRIB基序的蛋白（RICs）中的效应靶点，介导了两条对细胞极化具有相反作用的拮抗途径。ROP蛋白似乎直接与ARP2/3复合体的上游调节因子相互作用，ARP2/3复合体是肌动蛋白细胞骨架的保守调节因子。ROP功能依赖于1类ADP核糖基化因子（ARFs），ARFs是囊泡运输机制的核心成分，也参与PIN形成（PIN）家族生长素外流促进因子的极性定位。
