Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Academy of Sciences of the Czech Republic, Prague, Czech Republic, Czech Republic.
PLoS One. 2013 Jul 23;8(7):e70050. doi: 10.1371/journal.pone.0070050. Print 2013.
Auxin binding protein 1 (ABP1) is a putative auxin receptor and its function is indispensable for plant growth and development. ABP1 has been shown to be involved in auxin-dependent regulation of cell division and expansion, in plasma-membrane-related processes such as changes in transmembrane potential, and in the regulation of clathrin-dependent endocytosis. However, the ABP1-regulated downstream pathway remains elusive.
METHODOLOGY/PRINCIPAL FINDINGS: Using auxin transport assays and quantitative analysis of cellular morphology we show that ABP1 regulates auxin efflux from tobacco BY-2 cells. The overexpression of ABP1can counterbalance increased auxin efflux and auxin starvation phenotypes caused by the overexpression of PIN auxin efflux carrier. Relevant mechanism involves the ABP1-controlled vesicle trafficking processes, including positive regulation of endocytosis of PIN auxin efflux carriers, as indicated by fluorescence recovery after photobleaching (FRAP) and pharmacological manipulations.
CONCLUSIONS/SIGNIFICANCE: The findings indicate the involvement of ABP1 in control of rate of auxin transport across plasma membrane emphasizing the role of ABP1 in regulation of PIN activity at the plasma membrane, and highlighting the relevance of ABP1 for the formation of developmentally important, PIN-dependent auxin gradients.
生长素结合蛋白 1（ABP1）是一种假定的生长素受体，其功能对于植物的生长和发育是不可或缺的。已经表明，ABP1 参与了生长素依赖的细胞分裂和扩张的调节，参与了质膜相关过程，如跨膜电位的变化，以及网格蛋白依赖的内吞作用的调节。然而，ABP1 调节的下游途径仍然难以捉摸。
方法/主要发现：我们使用生长素运输测定和细胞形态的定量分析表明，ABP1 调节烟草 BY-2 细胞中的生长素外排。ABP1 的过表达可以抵消由 PIN 生长素外排载体的过表达引起的生长素外排增加和生长素饥饿表型。相关机制涉及 ABP1 控制的囊泡运输过程，包括通过荧光恢复后漂白（FRAP）和药理学操作指示的 PIN 生长素外排载体的内吞作用的正调节。
结论/意义：这些发现表明 ABP1 参与了质膜上生长素运输速率的控制，强调了 ABP1 在调节质膜上 PIN 活性中的作用，并突出了 ABP1 对形成与发育相关的、依赖 PIN 的生长素梯度的重要性。
