Klösgen R B, Weil J H
Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Strasbourg, France.
Mol Gen Genet. 1991 Feb;225(2):297-304. doi: 10.1007/BF00269862.
The transit peptide of the maize waxy protein (a nuclear-encoded amyloplast protein of the maize endosperm) was studied with respect to its role in subcellular protein targeting in transgenic potato plants. TP30, a chimeric precursor protein consisting of the waxy transit peptide and an additional 34 amino acids of the mature waxy protein fused to the beta-glucuronidase of Escherichia coli, was expressed in potato plants under the control of the 35S promoter of cauliflower mosaic virus. This fusion protein is imported not only into amyloplasts, the natural target organelles in the maize plant, but also into chloroplasts. In contrast, Gus, the beta-glucuronidase alone, which was also expressed in parallel experiments in transgenic potato plants is always found in the cytosol of the plant cells. As a consequence of the different subcellular locations of TP30 and Gus, we observed differences in the expression rates of the respective proteins in leaf cells, resulting in higher steady state levels of TP30 compared to Gus. In tuber cells, no correlation between intracellular location and expression of the proteins was found.
针对玉米蜡质蛋白（一种玉米胚乳的核编码造粉体蛋白）的转运肽在转基因马铃薯植株亚细胞蛋白质靶向中的作用进行了研究。TP30是一种嵌合前体蛋白，由蜡质转运肽和成熟蜡质蛋白额外的34个氨基酸与大肠杆菌β-葡萄糖醛酸酶融合而成，在花椰菜花叶病毒35S启动子的控制下在马铃薯植株中表达。这种融合蛋白不仅被导入玉米植株中的天然靶细胞器造粉体，还被导入叶绿体。相比之下，在转基因马铃薯植株的平行实验中同样表达的单独的β-葡萄糖醛酸酶Gus总是存在于植物细胞的细胞质中。由于TP30和Gus在亚细胞定位上的不同，我们观察到叶细胞中各自蛋白质的表达率存在差异，导致TP30的稳态水平高于Gus。在块茎细胞中，未发现蛋白质的细胞内定位与表达之间存在相关性。
