Torres E, Gonzalez-Melendi P, Stöger E, Shaw P, Twyman R M, Nicholson L, Vaquero C, Fischer R, Christou P, Perrin Y
Molecular Biotechnology Unit, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom.
Plant Physiol. 2001 Nov;127(3):1212-23.
We compared the subcellular distribution of native and artificial reticuloplasmins in endosperm, callus, and leaf tissues of transgenic rice (Oryza sativa) to determine the distribution of these proteins among endoplasmic reticulum (ER) and post-ER compartments. The native reticuloplasmin was calreticulin. The artificial reticuloplasmin was a recombinant single-chain antibody (scFv), expressed with an N-terminal signal peptide and the C-terminal KDEL sequence for retrieval to the ER (scFvT84.66-KDEL). We found that both molecules were distributed in the same manner. In endosperm, each accumulated in ER-derived prolamine protein bodies, but also in glutelin protein storage vacuoles, even though glutelins are known to pass through the Golgi apparatus en route to these organelles. This finding may suggest that similar mechanisms are involved in the sorting of reticuloplasmins and rice seed storage proteins. However, the presence of reticuloplasmins in protein storage vacuoles could also be due to simple dispersal into these compartments during protein storage vacuole biogenesis, before glutelin deposition. In callus and leaf mesophyll cells, both reticuloplasmins accumulated in ribosome-coated vesicles probably derived directly from the rough ER.
我们比较了天然和人工网质蛋白在转基因水稻（Oryza sativa）胚乳、愈伤组织和叶片组织中的亚细胞分布，以确定这些蛋白质在内质网（ER）和ER后区室之间的分布。天然网质蛋白是钙网蛋白。人工网质蛋白是一种重组单链抗体（scFv），其表达带有N端信号肽和用于返回内质网的C端KDEL序列（scFvT84.66-KDEL）。我们发现这两种分子的分布方式相同。在胚乳中，它们都积聚在内质网衍生的醇溶蛋白体中，但也存在于谷蛋白储存液泡中，尽管已知谷蛋白在前往这些细胞器的途中会经过高尔基体。这一发现可能表明，网质蛋白和水稻种子储存蛋白的分选涉及相似的机制。然而，网质蛋白在蛋白质储存液泡中的存在也可能是由于在谷蛋白沉积之前，在蛋白质储存液泡生物发生过程中简单地扩散到这些区室中。在愈伤组织和叶片叶肉细胞中，两种网质蛋白都积聚在可能直接源自粗糙内质网的核糖体包被小泡中。
