MAG4/Atp115 is a golgi-localized tethering factor that mediates efficient anterograde transport in Arabidopsis.
MAG4/Atp115 is a golgi-localized tethering factor that mediates efficient anterograde transport in Arabidopsis.
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DOI：
10.1093/pcp/pcq137
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发表时间：
2010-10
影响因子：
4.9
通讯作者：
Hideyuki Takahashi;K. Tamura;Junpei Takagi;Y. Koumoto;I. Hara-Nishimura;T. Shimada
中科院分区：
文献类型：
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作者：
Hideyuki Takahashi;K. Tamura;Junpei Takagi;Y. Koumoto;I. Hara-Nishimura;T. Shimada
种子储存蛋白在粗内质网（ER）上以前体形式合成，然后被转运到蛋白质储存液泡（psv）中，在那里它们被转化为成熟的形式。为了了解储存蛋白的转运机制，我们筛选了拟南芥突变体，以确定那些异常积累储存蛋白前体的突变体。在这里，我们描述了一个新的maigo突变体，maigo 4 (mag4)，它在干种子中异常地积累了两种主要储存蛋白的前体，12S球蛋白和2S白蛋白。电镜显示，镁4种子细胞异常发育出大量具有高电子密度核的新结构。其中一些结构被核糖体包围。免疫金分析表明，电子致密核是2S白蛋白前体的聚集，12S球蛋白定位于核周围。MAG4基因鉴定为At3g27530，其蛋白结构域与牛水疱转运因子p115的结构域同源。MAG4分子集中在顺式高尔基堆叠中。我们的研究结果表明，MAG4在植物中将储存蛋白前体从内质网转运到高尔基复合体中起作用。此外，mag4突变体表现出矮化表型，表明mag4既参与储存蛋白的运输，也参与植物的生长发育。
Seed storage proteins are synthesized on rough endoplasmic reticulum (ER) in a precursor form and then are transported to protein storage vacuoles (PSVs) where they are converted to their mature form. To understand the mechanisms by which storage proteins are transported, we screened Arabidopsis maigo mutants to identify those that abnormally accumulate storage protein precursors. Here we describe a new maigo mutant, maigo 4 (mag4), that abnormally accumulates the precursors of two major storage proteins, 12S globulin and 2S albumin, in dry seeds. Electron microscopy revealed that mag4 seed cells abnormally develop a large number of novel structures that exhibit a highly electron-dense core. Some of these structures were surrounded by ribosomes. Immunogold analysis suggests that the electron-dense core is an aggregate of 2S albumin precursors and that 12S globulins are localized around the core. The MAG4 gene was identified as At3g27530, and the MAG4 protein has domains homologous to those found in bovine vesicular transport factor p115. MAG4 molecules were concentrated at cis-Golgi stacks. Our findings suggest that MAG4 functions in the transport of storage protein precursors from the ER to the Golgi complex in plants. In addition, the mag4 mutant exhibits a dwarf phenotype, suggesting that MAG4 is involved in both the transport of storage proteins and in plant growth and development.