Rab2 GTPase regulates vesicle trafficking between the endoplasmic reticulum and the Golgi bodies and is important to pollen tube growth
Rab2 GTPase regulates vesicle trafficking between the endoplasmic reticulum and the Golgi bodies and is important to pollen tube growth
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DOI：
10.1105/tpc.000836
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发表时间：
2002-04-01
期刊：
影响因子：
11.6
通讯作者：
Wu, HM
中科院分区：
文献类型：
--
作者：
Cheung, AY;Chen, CYH;Wu, HM
花粉管的伸长依赖于花粉管顶端分泌大量的细胞膜和细胞壁物质来维持快速生长。已知RAS相关的小GTP酶的大家族Rabs或Ypts调节哺乳动物和酵母细胞中不同内膜隔室和质膜之间的运输囊泡的顺行和逆行运输。对类似植物蛋白的功能作用的研究正在兴起。我们在这里报告，烟草花粉占主导地位的Rab 2，NtRab 2，功能在内质网和高尔基体之间的分泌途径在伸长的花粉管。绿色荧光蛋白-NtRab 2融合蛋白定位于伸长花粉管的高尔基体。NtRab 2蛋白的显性负突变抑制了它们的高尔基体定位，阻断了高尔基体驻留以及质膜和分泌蛋白向其正常位置的递送，并抑制了花粉管生长。另一方面，当绿色荧光蛋白-NtRab 2在瞬时转化的叶原生质体和表皮细胞中过表达时，其中未观察到NtRab 2 mRNA积累到可检测的水平，这些蛋白质不能有效地靶向高尔基体。总之，这些观察结果表明，NtRab 2是重要的内质网和高尔基体之间的运输在花粉管，并可能专门以最佳方式支持这些尖端生长细胞的高分泌需求。
Pollen tube elongation depends on the secretion of large amounts of membrane and cell wall materials at the pollen tube tip to sustain rapid growth. A large family of RAS-related small GTPases, Rabs or Ypts, is known to regulate both anterograde and retrograde trafficking of transport vesicles between different endomembrane compartments and the plasma membrane in mammalian and yeast cells. Studies on the functional roles of analogous plant proteins are emerging. We report here that a tobacco pollen-predominant Rab2, NtRab2, functions in the secretory pathway between the endoplasmic reticulum and the Golgi in elongating pollen tubes. Green fluorescent protein-NtRab2 fusion protein localized to the Golgi bodies in elongating pollen tubes. Dominant-negative mutations in NtRab2 proteins inhibited their Golgi localization, blocked the delivery of Golgi-resident as well as plasmalemma and secreted proteins to their normal locations, and inhibited pollen tube growth. On the other hand, when green fluorescent protein-NtRab2 was over-expressed in transiently transformed leaf protoplasts and epidermal cells, in which NtRab2 mRNA have not been observed to accumulate to detectable levels, these proteins did not target efficiently to Golgi bodies. Together, these observations indicate that NtRab2 is important for trafficking between the endoplasmic reticulum and the Golgi bodies in pollen tubes and may be specialized to optimally support the high secretory demands in these tip growth cells.