Two Structural Domains Mediate Two Sequential Events in [gamma]-Zein Targeting: Protein Endoplasmic Reticulum Retention and Protein Body Formation.
Two Structural Domains Mediate Two Sequential Events in [gamma]-Zein Targeting: Protein Endoplasmic Reticulum Retention and Protein Body Formation.
复制标题
两个结构域介导γ-玉米醇溶蛋白靶向中的两个连续事件：蛋白质内质网保留和蛋白体形成。
DOI：
10.1105/tpc.6.12.1911
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
M. Ludevid
中科院分区：
文献类型：
--
作者：
M. Geli;M. Torrent;M. Ludevid
[伽马]-玉米醇溶蛋白是一种由胚乳细胞合成的玉米贮藏蛋白，与[α]和[β]-玉米醇溶蛋白一起储存在称为蛋白体的特殊细胞器中。以往的研究表明，在玉米中只有一种类型的蛋白体，它直接来自内质网(ER)。在这篇文章中，我们描述了[Gamma]-Zein参与内质网保留的结构域和参与蛋白体形成的结构域。为了确定在内质网衍生的蛋白体中负责[Gamma]-Zein保留的信号，构建了编码[Gamma]-Zein的各种缺失突变体的DNA，并将其作为异源系统导入拟南芥。通过脉冲追逐实验和免疫电子显微镜，我们证明了在[Gamma]-Zein的N端富含Pro的区域的缺失结束了它在内质网中的滞留，从而导致突变蛋白的分泌。内质网保留所需的[Gamma]-Zein的氨基酸序列是由八个单位的六肽PPPVHL组成的重复结构域。此外，我们观察到，只有那些同时含有富含Pro重复结构域和C末端富含半胱氨酸结构域的[Gamma]-Zein突变体才能形成内质网衍生的蛋白体。我们认为，[Gamma]-Zein在内质网中的保留可能是蛋白质-蛋白质结合或重复结构域与内质网膜瞬时相互作用的结果。
[gamma]-Zein is a maize storage protein synthesized by endosperm cells and stored together with [alpha]- and [beta]-zeins in specialized organelles called protein bodies. Previous studies have shown that in maize there is only one type of protein body and it is derived directly from the endoplasmic reticulum (ER). In this article, we describe the domains of [gamma]-zein involved in ER retention and the domains involved in protein body formation. To identify the signal responsible for [gamma]-zein retention in ER-derived protein bodies, DNAs encoding various deletion mutants of [gamma]-zein were constructed and introduced into Arabidopsis as a heterologous system. By using pulse-chase experiments and immunoelectron microscopy, we demonstrated that the deletion of a proline-rich domain at the N terminus of [gamma]-zein puts an end to its retention in the ER; this resulted in the secretion of the mutated protein. The amino acid sequence of [gamma]-zein necessary for ER retention is the repeat domain composed of eight units of the hexapeptide PPPVHL. In addition, we observed that only those [gamma]-zein mutants that contained both the proline-rich repeat domain and the C-terminal cysteine-rich domain were able to form ER-derived protein bodies. We suggest that the retention of [gamma]-zein in the ER could be a result of a protein-protein association or a transient interaction of the repeat domain with ER membranes.