PDF(Sci-hub)
Abstract：
Polarized cell growth in plants is maintained under the strict control and exquisitely choreographed balance of exocytic and endocytic membrane trafficking. The pollen tube has become a model system for rapid polar growth in which delivery of cell wall material and membrane recycling are controlled by membrane trafficking. Endocytosis plays an important role that is poorly understood. The plant AP180 N-Terminal Homolog (ANTH) proteins are putative homologs of Epsin 1 that recruits clathrin to phosphatidylinositol 4, 5-bisphosphate (PIP2) containing membranes to facilitate vesicle budding during endocytosis. Two Arabidopsis ANTH encoded by the genes AtAP180 and AtECA2 are highly expressed in pollen tubes. Pollen tubes from T-DNA inserted knockout mutant lines display significant morphological defects and unique pectin deposition. Fluorescent tagging reveals organization into dynamic foci located at the lateral flanks of the pollen tube. This precisely defined subapical domain coincides which clathrin-mediated endocytosis (CME) and PIP2 localization. Using a liposome-protein binding test, we showed that AtECA2 protein and ANTH domain recombinant proteins have strong affinity to PIP2 and phosphatidic acid containing liposomes in vitro. Taken together these data suggest that Arabidopsis ANTH proteins may play an important role in CME, proper cell wall assembly and morphogenesis.
摘要：
植物中的极化细胞生长保持在严格控制和胞吞和内吞膜运输的精心编排的平衡下。花粉管已成为快速极性生长的模型系统，其中细胞壁材料的输送和膜再循环由膜运输控制。细胞内吞作用起着重要的作用，人们对此知之甚少。植物AP180N末端同源物（ANTH）蛋白是Epsin1的推定同源物，可将网格蛋白募集到含有磷脂酰肌醇4，5-二磷酸（PIP2）的膜上，以促进内吞过程中的囊泡出芽。由AtAP180和AtECA2基因编码的两个拟南芥ANTH在花粉管中高度表达。来自T-DNA插入的敲除突变系的花粉管显示出明显的形态缺陷和独特的果胶沉积。荧光标记显示组织成位于花粉管侧面的动态病灶。此精确定义的根尖下结构域与网格蛋白介导的内吞作用（CME）和PIP2定位相吻合。用脂质体-蛋白结合试验,我们表明AtECA2蛋白和ANTH域重组蛋白在体外对PIP2和含磷脂酸的脂质体有很强的亲和力。综合这些数据表明，拟南芥ANTH蛋白可能在CME中起重要作用，适当的细胞壁组装和形态发生。
