Biosynthesis and immunolocalization of Lewis a-containing N-glycans in the plant cell
Biosynthesis and immunolocalization of Lewis a-containing N-glycans in the plant cell
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DOI：
10.1104/pp.121.2.333
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发表时间：
1999-10-01
期刊：
影响因子：
7.4
通讯作者：
Hawes, C
中科院分区：
文献类型：
--
作者：
Fitchette, AC;Cabanes-Macheteau, M;Hawes, C
我们最近证明了植物糖蛋白上存在一种新的天冬酰胺连接的复合聚糖，其含有刘易斯a（Le（a））或Gal β（1-3）[Fuc alpha（1-4）]GlcNAc表位，其在哺乳动物细胞中发挥着重要作用在细胞与细胞识别中。在这里，我们表明，单克隆抗体JIM 84，这是广泛使用的高尔基体标记在光和电子显微镜的植物细胞，是特异性的Le（a）抗原。这种抗原存在于许多开花和非开花植物的糖蛋白上，但在十字花科（包括拟南芥的家族）中不太明显。在高尔基体中发现了含Le（a）的寡糖，我们的免疫细胞化学实验表明它是在高尔基体的反式部分合成的。Le（a）表位大量存在于可溶性或膜结合的胞外糖蛋白上，但从未在液泡糖蛋白上观察到。双标记实验表明，液泡糖蛋白不会绕过Le（a）构建的晚期高尔基室，并且液泡糖蛋白中没有莱亚表位可能是其在到达液泡途中或到达液泡后被糖苷酶降解的结果。
We recently demonstrated the presence of a new asparagine-linked complex glycan on plant glycoproteins that harbors the Lewis a (Le(a)), or Gal beta(1-3)[Fuc alpha(1-4)]GlcNAc, epitope, which in mammalian cells plays an important role in cell-to-cell recognition. Here we show that the monoclonal antibody JIM 84, which is widely used as a Golgi marker in light and electron microscopy of plant cells, is specific for the Le(a) antigen. This antigen is present on glycoproteins of a number of flowering and non-flowering plants, but is less apparent in the Cruciferae, the family that includes Arabidopsis. Le(a)-containing oligosaccharides are found in the Golgi apparatus, and our immunocytochemical experiments suggest that it is synthesized in the trans-most part of the Golgi apparatus. Le(a) epitopes are abundantly present on extracellular glycoproteins, either soluble or membrane bound, but are never observed on vacuolar glycoproteins. Double-labeling experiments suggest that vacuolar glycoproteins do not bypass the late Golgi compartments where Le(a) is built, and that the absence of the Lea epitope from vacuolar glycoproteins is probably the result of its degradation by glycosidases en route to or after arrival in the vacuole.