Mass Transport of Proform of a Kdel-Tailed Cysteine Proteinase (Sh-EP) to Protein Storage Vacuoles by Endoplasmic Reticulum–Derived Vesicle Is Involved in Protein Mobilization in Germinating Seeds
Mass Transport of Proform of a Kdel-Tailed Cysteine Proteinase (Sh-EP) to Protein Storage Vacuoles by Endoplasmic Reticulum–Derived Vesicle Is Involved in Protein Mobilization in Germinating Seeds
复制标题
通过内质网衍生囊泡将 Kdel 尾半胱氨酸蛋白酶 (Sh-EP) 的原形大量转运至蛋白质储存液泡，参与发芽种子中的蛋白质动员
DOI：
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发表时间：
2000
影响因子：
7.8
通讯作者：
T. Minamikawa
中科院分区：
文献类型：
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作者：
K. Toyooka;T. Okamoto;T. Minamikawa
一种被称为SH-EP的空泡半胱氨酸蛋白酶在萌发的芒戈种子子叶中表达，并负责贮藏蛋白的降解。SH-EP是一种具有cooh末端内质网保留序列（KDEL）的特征性空泡蛋白酶。本研究利用7种抗体对萌发的芒戈种子子叶细胞进行免疫细胞化学分析，以确定SH-EP从内质网到蛋白储存液泡的细胞内转运途径。在内质网中合成的一种SH-EP形式积聚在内质网边缘或中间形成转运囊泡的区域。含有大量proSH-EP的囊泡，称为KV，从内质网脱离，绕过高尔基复合体，并被分类为蛋白质储存液泡。SH-EP通过KV的大量转运被认为介导了萌发种子子叶细胞的动态蛋白质动员。我们讨论了KDEL尾部空泡型半胱氨酸蛋白酶的KDEL序列作为内质网积累信号的可能性，以及内质网衍生的kv样囊泡对蛋白酶的质量运输参与植物蛋白动员的可能性。
A vacuolar cysteine proteinase, designated SH-EP, is expressed in the cotyledon of germinated Vigna mungo seeds and is responsible for the degradation of storage proteins. SH-EP is a characteristic vacuolar proteinase possessing a COOH-terminal endoplasmic reticulum (ER) retention sequence, KDEL. In this work, immunocytochemical analysis of the cotyledon cells of germinated V. mungo seeds was performed using seven kinds of antibodies to identify the intracellular transport pathway of SH-EP from ER to protein storage vacuoles. A proform of SH-EP synthesized in ER accumulated at the edge or middle region of ER where the transport vesicle was formed. The vesicle containing a large amount of proSH-EP, termed KV, budded off from ER, bypassed the Golgi complex, and was sorted to protein storage vacuoles. This massive transport of SH-EP via KV was thought to mediate dynamic protein mobilization in the cotyledon cells of germinated seeds. We discuss the possibilities that the KDEL sequence of KDEL-tailed vacuolar cysteine proteinases function as an accumulation signal at ER, and that the mass transport of the proteinases by ER-derived KV-like vesicle is involved in the protein mobilization of plants.