MAIGO2 is involved in exit of seed storage proteins from the endoplasmic reticulum in Arabidopsis thaliana
MAIGO2 is involved in exit of seed storage proteins from the endoplasmic reticulum in Arabidopsis thaliana
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DOI：
10.1105/tpc.106.046151
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发表时间：
2006-12-01
期刊：
影响因子：
11.6
通讯作者：
Hara-Nishimura, Ikuko
中科院分区：
文献类型：
--
作者：
Li, Lixin;Shimada, Tomoo;Hara-Nishimura, Ikuko
种子贮藏蛋白是在内质网(ER)上合成的前体，然后被运输到蛋白质贮藏液泡，在那里它们被加工成成熟的形式。在这里，我们分离了一个拟南芥突变体maigo2(Mag2)，它在干燥的种子中积累了两种主要贮藏蛋白-2S白蛋白和12S球蛋白的前体。MAG2种子细胞包含许多新的结构，其核心是由2S白蛋白前体组成的电子致密核心。12S球蛋白是从2S白蛋白中分离出来的，并与在MAG2种子中含量更丰富的内质网伴侣、腔结合蛋白和蛋白质二硫键异构酶一起定位于结构的基质区域。MAG2基因被鉴定为AT3g47700，MAG2蛋白在C-末端有一个Rint-1/TIP20结构域。我们发现一些MAG2分子与内质网结合在一起。MAG2能与两个内质网定位的t-SNARs结合(靶向可溶性NSF[N-乙基马来酰亚胺敏感融合蛋白]附着蛋白受体，分别位于Sec20和Ufe1)。我们的发现表明，MAG2在植物的内质网和高尔基复合体之间的贮藏蛋白前体的运输中发挥作用。
Seed storage proteins are synthesized on the endoplasmic reticulum ( ER) as precursors and then transported to protein storage vacuoles, where they are processed into mature forms. Here, we isolated an Arabidopsis thaliana mutant, maigo2 (mag2), that accumulated the precursors of two major storage proteins, 2S albumin and 12S globulin, in dry seeds. mag2 seed cells contained many novel structures, with an electron-dense core that was composed of the precursor forms of 2S albumin. 12S globulins were segregated from 2S albumin and were localized in the matrix region of the structures together with the ER chaperones lumenal binding protein and protein disulfide isomerase, which were more abundant in mag2 seeds. The MAG2 gene was identified as At3g47700, and the MAG2 protein had a RINT-1/TIP20 domain in the C-terminal region. We found that some MAG2 molecules were peripherally associated with the ER membrane. MAG2 had an ability to bind to two ER-localized t-SNAREs ( for target-soluble NSF [N-ethylmaleimide-sensitive fusion protein] attachment protein receptor; At Sec20 and At Ufe1). Our findings suggest that MAG2 functions in the transport of storage protein precursors between the ER and Golgi complex in plants.