TONOPLAST AND SOLUBLE VACUOLAR PROTEINS ARE TARGETED BY DIFFERENT MECHANISMS
TONOPLAST AND SOLUBLE VACUOLAR PROTEINS ARE TARGETED BY DIFFERENT MECHANISMS
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DOI：
10.1105/tpc.5.9.1113
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发表时间：
1993-09-01
期刊：
影响因子：
11.6
通讯作者：
CHRISPEELS, MJ
中科院分区：
文献类型：
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作者：
GOMEZ, L;CHRISPEELS, MJ
分泌系统将蛋白质递送至液泡及其限制膜（液泡膜）被认为是一种解离过程，其中囊泡从一个室中出芽并与另一个室融合。我们研究了从用编码这两种蛋白质的基因转化的转基因烟草植物获得的叶肉原生质体中植物血凝素（PHA）和液泡膜内在蛋白（TIP）的转运动力学。在脉冲追踪实验中，发现 PHA 到达液泡（合成后 24 小时完成）比 TIP 到达液泡膜（合成后 6 小时完成）慢。 Brefeldin A 和莫能菌素通过干扰特定的囊泡转运步骤来阻断蛋白质转运。布雷菲德菌素 A 阻止内质网和高尔基体之间的顺行囊泡运输，而莫能菌素则通过破坏跨膜质子梯度来抑制跨高尔基体网络中的正确排序。两种抑制剂都能阻断 PHA 向液泡的运输，并改变高尔基体酶处理其复杂聚糖的速率。这两种药物都不能阻止 TIP 到达液泡膜，这表明在这些抑制剂存在的情况下，囊泡的流动仍在继续。我们认为 PHA 等可溶性蛋白和 TIP 等膜蛋白通过不同的路径到达其液泡目的地。
The delivery of proteins to the vacuole and its limiting membrane (the tonoplast) by the secretory system is thought to be a dissociative process in which vesicles bud from one compartment and fuse with another. We studied the transport kinetics of phytohemagglutinin (PHA) and tonoplast intrinsic protein (TIP) in mesophyll protoplasts obtained from transgenic tobacco plants transformed with genes encoding these two proteins. In pulse-chase experiments, arrival of PHA in the vacuole was found to be slower (completed 24 hr after synthesis) than the arrival of TIP in the tonoplast (completed 6 hr after synthesis). Brefeldin A and monensin block protein transport by interfering in specific vesicle transport steps. Brefeldin A prevents anterograde vesicle transport between the endoplasmic reticulum and the Golgi, whereas monensin inhibits correct sorting in the trans-Golgi network by disrupting the proton gradient across the membrane. Both inhibitors blocked the transport of PHA to the vacuole and altered the rate at which its complex glycan is processed by Golgi enzymes. Neither drug stopped the arrival of TIP in the tonoplast, suggesting that the flow of vesicles continues in the presence of these inhibitors. We suggest that soluble proteins like PHA and membrane proteins like TIP reach their vacuolar destinations by different paths.