Department of Plant Physiology and Molecular Plant Biology, Eötvös Loránd University, Budapest, Hungary.
Ann Bot. 2014 Apr;113(5):807-15. doi: 10.1093/aob/mcu008. Epub 2014 Mar 5.
The trafficking of proteins in the endoplasmic reticulum (ER) of plant cells is a topic of considerable interest since this organelle serves as an entry point for proteins destined for other organelles, as well as for the ER itself. In the current work, transgenic rice was used to study the pattern and pathway of deposition of the wheat high molecular weight (HMW) glutenin sub-unit (GS) 1Dx5 within the rice endosperm using specific antibodies to determine whether it is deposited in the same or different protein bodies from the rice storage proteins, and whether it is located in the same or separate phases within these.
The protein distribution and the expression pattern of HMW sub-unit 1Dx5 in transgenic rice endosperm at different stages of development were determined using light and electron microscopy after labelling with antibodies.
The use of HMW-GS-specific antibodies showed that sub-unit 1Dx5 was expressed mainly in the sub-aleurone cells of the endosperm and that it was deposited in both types of protein body present in the rice endosperm: derived from the ER and containing prolamins, and derived from the vacuole and containing glutelins. In addition, new types of protein bodies were also formed within the endosperm cells.
The results suggest that the HMW 1Dx5 protein could be trafficked by either the ER or vacuolar pathway, possibly depending on the stage of development, and that its accumulation in the rice endosperm could compromise the structural integrity of protein bodies and their segregation into two distinct populations in the mature endosperm.
植物细胞内质网（ER）中蛋白质的运输是一个备受关注的话题，因为该细胞器是蛋白质进入其他细胞器以及内质网本身的入口。在当前的工作中，使用转基因水稻研究了小麦高分子量（HMW）谷蛋白亚基（GS）1Dx5 在水稻胚乳中的沉积模式和途径，使用特定的抗体来确定它是否沉积在与水稻贮藏蛋白相同或不同的蛋白体中，以及它是否位于这些蛋白体的相同或不同相中。
使用抗体标记后，通过光镜和电子显微镜确定了转基水稻胚乳在不同发育阶段的蛋白质分布和 HMW 亚基 1Dx5 的表达模式。
使用 HMW-GS 特异性抗体表明，亚基 1Dx5 主要在胚乳的亚糊粉层细胞中表达，并且沉积在水稻胚乳中存在的两种蛋白体中：一种来自内质网，含有醇溶蛋白，另一种来自液泡，含有谷蛋白。此外，在胚乳细胞内还形成了新类型的蛋白体。
结果表明，HMW 1Dx5 蛋白可以通过内质网或液泡途径运输，可能取决于发育阶段，其在水稻胚乳中的积累可能会破坏蛋白体的结构完整性，并使其在成熟胚乳中分离成两个不同的群体。
