The green microalgae synthesizes a -glycan precursor within the endoplasmic reticulum (ER) that is then transferred to specific asparagine residues of the protein -glycosylation consensus sites. Maturation of this precursor in the ER and then in the Golgi apparatus results in -glycans composed of a non-canonical linear ManGlcNAc that is partially -methylated and carries out one or two xylose residues. One xylose residue was demonstrated to be a core beta(1,2)-xylose. Recently, two xylosyltransferases, named A () and B () respectively, were demonstrated to be responsible for the addition of this core beta(1,2)-xylose. Nowadays, even if information is available regarding the protein -glycosylation pathway and especially the core beta(1,2)-xylosylation in no data regarding the subcellular localization of this subset of glycosylated proteins is available. Therefore, in this work, subcellular immunolocalization of -glycoproteins bearing the core beta(1,2)-xylose epitope was carried out using an optimized protocol of transmission electron microscopy of CC-5325 and CC-5155 reference strains (wild types) compared to the MxIM double insertional mutant strain in which the core beta(1,2)-xylosylation is fully-lacking. Such a study gives a first cartography of specific glycoepitopes in microalgae and new insights on the distribution of core beta(1,2)-xylosylated glycoproteins in organelles.

中文翻译：

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绿色微藻莱茵衣藻核心β(1,2)-木糖基化N-糖蛋白的亚细胞定位

绿色微藻在内质网（ER）内合成α-聚糖前体，然后将其转移到蛋白质-糖基化共有位点的特定天冬酰胺残基。该前体在 ER 中成熟，然后在高尔基体中成熟，产生由非典型线性 ManGlcNAc 组成的 β-聚糖，其部分甲基化并带有一个或两个木糖残基。一个木糖残基被证明是核心β(1,2)-木糖。最近，两种木糖基转移酶，分别命名为 A () 和 B ()，被证明负责添加该核心 β(1,2)-木糖。如今，即使有关于蛋白质糖基化途径，特别是核心β(1,2)-木糖基化的信息，也没有关于该糖基化蛋白质子集的亚细胞定位的数据。因此，在这项工作中，使用 CC-5325 和 CC-5155 参考菌株（野生型）的透射电子显微镜优化方案，对带有核心 β(1,2)-木糖表位的 β-糖蛋白进行亚细胞免疫定位。 MxIM 双插入突变株，其中核心 β(1,2)-木糖基化完全缺失。这项研究首次绘制了微藻中特定糖表位的图谱，并对细胞器中核心 β(1,2)-木糖化糖蛋白的分布有了新的见解。