Butler J H, Hu S, Brady S R, Dixon M W, Muday G K
Wake Forest University, Department of Biology, Winston-Salem, NC 27109, USA.
Plant J. 1998 Feb;13(3):291-301. doi: 10.1046/j.1365-313x.1998.00017.x.
The N-1-naphthylphthalamic acid (NPA)-binding protein is part of the auxin efflux carrier, the protein complex that controls polar auxin transport in plant tissues. This study tested the hypothesis that the NPA-binding protein (NBP) is associated with the actin cytoskeleton in vitro and that an intact actin cytoskeleton is required for polar auxin transport in vivo. Cytoskeletal polymerization was altered in extracts of zucchini hypocotyls with reagents that stabilized either the polymeric or monomeric forms of actin or tubulin. Phalloidin treatment altered actin polymerization, as demonstrated by immunoblot analyses following native and denaturing electrophoresis. Phalloidin increased both filamentous actin (F-actin) and NPA-binding activity, while cytochalasin D and Tris decreased both F-actin and NPA-binding activity in cytoskeletal pellets. The microtubule stabilizing drug taxol increased pelletable tubulin, but did not alter either the amount of pelletable actin or NPA-binding activity. Treatment of etiolated zucchini hypocotyls with cytochalasin D decreased the amount of auxin transport and its regulation by NPA. These experimental results are consistent with an in vitro actin cytoskeletal association of the NPA-binding protein and with the requirement of an intact actin cytoskeleton for maximal polar auxin transport in vivo.
N-1-萘基邻苯二甲酸（NPA）结合蛋白是生长素输出载体的一部分，该蛋白复合体控制植物组织中的极性生长素运输。本研究检验了以下假设：NPA结合蛋白（NBP）在体外与肌动蛋白细胞骨架相关，并且完整的肌动蛋白细胞骨架是体内极性生长素运输所必需的。用稳定肌动蛋白或微管蛋白的聚合形式或单体形式的试剂改变西葫芦下胚轴提取物中的细胞骨架聚合。鬼笔环肽处理改变了肌动蛋白聚合，天然和变性电泳后的免疫印迹分析证明了这一点。鬼笔环肽增加了丝状肌动蛋白（F-肌动蛋白）和NPA结合活性，而细胞松弛素D和Tris降低了细胞骨架沉淀中的F-肌动蛋白和NPA结合活性。微管稳定药物紫杉醇增加了可沉淀的微管蛋白，但未改变可沉淀的肌动蛋白量或NPA结合活性。用细胞松弛素D处理黄化西葫芦下胚轴降低了生长素运输量及其受NPA的调节。这些实验结果与NPA结合蛋白在体外与肌动蛋白细胞骨架的关联以及体内最大极性生长素运输需要完整的肌动蛋白细胞骨架一致。
