C.N.R.S.-UA 203, Université de Rouen, Faculté des Sciences, F-76130, Mont Saint Aignan, France.
Planta. 1989 Dec;180(1):96-104. doi: 10.1007/BF02411415.
Suspension-cultured cells of sycamore (Acer pseudoplatanus L.) secrete a number of acid hydrolases and other proteins that have both highmannose and complex asparagine-linked glycans. We used affinity chromatography with concanavalin A and an antiserum specific for complex glycans in conjunction with in vivo-labeling studies to show that all of the secreted proteins carry glycans. The presence of complex glycans on secretory proteins indicates that they are passing through the Golgi complex on the way to the extracellular compartment. The sodium ionophore, monensin, did not block the transport of proteins to the extracellular medium, even though monensin efficiently inhibited the Golgi-mediated processing of complex glycans. The inhibition of N-glycosylation by tunicamycin reduced by 76% to 84% the accumulation of newly synthesized (i.e. radioactively labeled) protein that was secreted by the sycamore cells, while cytoplasmic protein biosynthesis was not affected by this antibiotic. However, in the presence of glycoprotein-processing inhibitors, such as castanospermine and deoxymannojirimycin, the formation of complex glycans was prevented but glycoprotein secretion was unchanged. These results support the conclusion that N-linked glycan processing is not necessary for sorting, but glycosylation is required for accumulation of secreted proteins in the extracellular compartment.
悬浮培养的悬铃木（Acer pseudoplatanus L.）细胞分泌许多酸性水解酶和其他蛋白质，这些蛋白质既有高甘露糖型又有复杂天冬酰胺连接的聚糖。我们使用伴刀豆球蛋白 A 的亲和层析和针对复杂聚糖的抗血清，结合体内标记研究，表明所有分泌的蛋白质都带有聚糖。分泌蛋白上存在复杂的聚糖表明它们在向细胞外腔运输的过程中通过了高尔基体复合物。钠离子载体莫能霉素并没有阻止蛋白质向细胞外介质的运输，尽管莫能霉素有效地抑制了高尔基体对复杂聚糖的加工。衣霉素抑制 N-糖基化，使新合成的（即放射性标记的）由悬铃木细胞分泌的蛋白质的积累减少了 76% 到 84%，而细胞质蛋白生物合成不受这种抗生素的影响。然而，在糖蛋白加工抑制剂（如苦柯子碱和脱氧甘露庚酮糖）存在的情况下，复杂聚糖的形成被阻止，但糖蛋白分泌没有变化。这些结果支持这样的结论，即 N-连接糖基化处理对于分拣不是必需的，但糖基化对于在细胞外腔中积累分泌蛋白是必需的。
