PROPOSAL FOR A COMMON OLIGOSACCHARIDE INTERMEDIATE IN SYNTHESIS OF MEMBRANE GLYCOPROTEINS
PROPOSAL FOR A COMMON OLIGOSACCHARIDE INTERMEDIATE IN SYNTHESIS OF MEMBRANE GLYCOPROTEINS
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DOI：
10.1016/0092-8674(77)90153-2
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发表时间：
1977-01-01
期刊：
影响因子：
64.5
通讯作者：
WIRTH, DF
中科院分区：
文献类型：
--
作者：
ROBBINS, PW;HUBBARD, SC;WIRTH, DF
内切-β-N-乙酰氨基葡萄糖苷酶H(Endo H)是一种作用于含有5个或5个以上甘露糖残基的天冬酰胺和脂联寡糖的酶。复合低聚糖和糖肽完全抵抗这种酶的作用。用~(35)S-蛋氨酸和~3H-甘露糖在未感染细胞[鸡胚成纤维细胞]以及在感染辛德比斯病毒和水泡性口炎病毒(VSV)的细胞中进行脉冲追逐实验。在每种情况下，用聚丙烯酰胺凝胶电泳法和凝胶过滤法分析标记材料对Endo H的敏感性。Endo H从脉冲标记的蛋白质中释放出所有标记的甘露糖。最初，释放的物质在大小上几乎与相同细胞中存在的脂联寡糖衍生的Endo H裂解产物相同。在Chase期间，35S-蛋氨酸和~3H-甘露糖蛋白对该酶的抵抗力越来越强。在追逐过程中，蛋白质释放的~3H-甘露糖标记的物质比从脂质中释放的寡糖要小。在天冬酰胺残基的糖基化过程中，一种常见的低聚糖可能会从脂质载体转移到蛋白质上，然后被加工成所谓的高甘露糖和复合低聚糖。根据现有证据，脂质连接的低聚糖含有2 N-乙酰氨基葡萄糖、8-12甘露糖和1-2个葡萄糖分子，似乎碳水化合物加工系统可能去除了一半或更多的甘露糖和所有糖基残基，最终形成复杂的糖肽。甘露糖和葡萄糖残留物的去除也可能发生在注定要成为成熟的高甘露糖肽的部位。
Endo-.beta.-N-acetylglucosaminidase H (endo H) is an enzyme which acts on asparagine- and lipid-linked oligosaccharides containing 5 or more mannose residues. Complex oligosaccharides and glycopeptides are completely resistant to the action of the enzyme. Pulse-chase experiments with 35S-methionine and 3H-mannose in uninfected cells [chicken embryo fibroblasts] and in cells infected with Sindbis virus and vesicular stomatitis virus (VSV). In each case, the labeled materials were analyzed for sensitivity to endo H by polyacrylamide gel electrophoresis and gel filtration. Endo H releases all the labeled mannose from pulse-labeled proteins. Initially, the released material is nearly identical in size to the endo H cleavage product derived from lipid-linked oligosaccharides present in the same cells. During chase periods, 35S-methionine and 3H-mannose protein becomes increasingly resistant to the enzyme. The 3H-mannose-labeled material released from the protein during chase periods is smaller in size than the oligosaccharide from the lipid. During glycosylation of asparagine residues, a common oligosaccharide is probably transferred from the lipid carrier to protein and is subsequently processed to yield the so-called high mannose and complex oligosaccharides. Based on present evidence, the lipid-linked oligosaccharide contains 2 N-acetylglucosamine, 8-12 mannose and 1-2 glucose molecules, it seems probable that the carbohydrate-processing systems remove half or more of the mannose and all of the glucose residues at sites destined to become complex glycopeptides. Removal of mannose and glucose residues may also occur at sites destined to become mature high mannose glycopeptides.