Lending C R, Larkins B A
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907.
Plant Cell. 1989 Oct;1(10):1011-23. doi: 10.1105/tpc.1.10.1011.
Zeins, the seed storage proteins of maize, are synthesized during endosperm development by membrane-bound polyribosomes and transported into the lumen of the endoplasmic reticulum, where they assemble into protein bodies. To better understand the distribution of the various zeins throughout the endosperm, and within protein bodies, we used immunolocalization techniques with light and electron microscopy to study endosperm tissue at 14 days and 18 days after pollination. Protein bodies increase in size with distance from the aleurone layer of the developing endosperm; this reflects a process of cell maturation. The protein bodies within the subaleurone cell layer are the smallest and contain little or no alpha-zein; beta-zein and gamma-zein are distributed throughout these small protein bodies. The protein bodies in cells farther away from the aleurone layer are progressively larger, and immunostaining for alpha-zein occurs over locules in the central region of these protein bodies. In the interior of the largest protein bodies, the locules of alpha-zein are fused. Concomitant with the appearance of alpha-zein in the central regions of the protein bodies, most of the beta- and gamma-zeins become peripheral. These observations are consistent with a model in which specific zeins interact to assemble the storage proteins into a protein body.
玉米醇溶蛋白是玉米的种子贮藏蛋白，在胚乳发育过程中由膜结合多核糖体合成，并转运到内质网腔中，在那里它们组装成蛋白体。为了更好地了解各种玉米醇溶蛋白在整个胚乳以及蛋白体内的分布情况，我们使用免疫定位技术结合光学显微镜和电子显微镜，对授粉后14天和18天的胚乳组织进行了研究。蛋白体的大小随着与发育中胚乳糊粉层距离的增加而增大，这反映了细胞成熟的过程。糊粉层下细胞层内的蛋白体最小，几乎不含或不含α-玉米醇溶蛋白；β-玉米醇溶蛋白和γ-玉米醇溶蛋白分布于这些小蛋白体中。离糊粉层较远的细胞中的蛋白体逐渐变大，α-玉米醇溶蛋白的免疫染色出现在这些蛋白体中央区域的腔室中。在最大蛋白体的内部，α-玉米醇溶蛋白的腔室融合在一起。随着α-玉米醇溶蛋白在蛋白体中央区域的出现，大部分β-和γ-玉米醇溶蛋白位于外周。这些观察结果与一个模型相符，即特定的玉米醇溶蛋白相互作用，将贮藏蛋白组装成蛋白体。
