The phosphorylation pattern of oligosaccharides in secreted procathepsin D is glycosylation site-specific and independent of the expression of mannose 6-phosphate receptors
The phosphorylation pattern of oligosaccharides in secreted procathepsin D is glycosylation site-specific and independent of the expression of mannose 6-phosphate receptors
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DOI：
10.1074/jbc.272.2.852
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发表时间：
1997-01-10
影响因子：
4.8
通讯作者：
vonFigura, K
中科院分区：
文献类型：
--
作者：
Dittmer, F;Pohlmann, R;vonFigura, K
哺乳动物细胞含有两种类型的甘露糖6-磷酸受体(MPR)，MPR 46和MPR 300，它们对单个溶酶体蛋白的分选有不同的作用。为了评价磷酸化低聚糖在两种受体分选效率中的作用，分析了在缺乏MPR 46和/或MPR 300的细胞中逃避分选的溶酶体蛋白上的磷酸化低聚糖的结构。Procathepsin D被选为模型是因为它能通过MPR 300有效地分选，而通过MPR 46分选得很差，并且在其两个N糖基化位点中的任何一个含有明显且高度不均一的磷酸化低聚糖混合物，MPR 46和300都被发现对原Athepsin D和其他溶酶体蛋白有轻微但明显的偏好，这些溶酶体蛋白含有带有两个磷酸单酯的寡糖。然而，原蛋白D和其他在对照细胞或缺乏MPR 46和/或MPR 300的细胞中逃脱分选的溶酶体蛋白中寡糖的磷酸化惊人地相似，含有两个磷酸单酯的寡糖代表了主要的寡糖种类。根据这些结果，我们得出结论，磷酸基团的位置、潜在寡糖的结构和/或溶酶体蛋白的多肽骨架在决定与MPR的亲和力方面起着主要作用。
Mammalian cells contain two types of mannose 6-phosphate receptors (MPR), MPRs 46 and 300, that contribute with variable efficiency to the sorting of individual lysosomal proteins. To evaluate the role of phosphorylated oligosaccharides for the sorting efficiency by either of the two receptors, the structure of phosphorylated oligosaccharides on lysosomal proteins escaping sorting in cells lacking MPR 46 and/or MPR 300 was analyzed. Procathepsin D was chosen as a model because it is sorted efficiently via MPR 300 and poorly via MPR 46 and contains a distinct and highly heterogenous mixture of phosphorylated oligosaccharides at either of its two N glycosylation sites, Both MPRs 46 and 300 were found to have a minor but distinct preference for forms of procathepsin D and other lysosomal proteins containing oligosaccharides with two phosphomonoesters. However, the phosphorylation of oligosaccharides in procathepsin D and other lysosomal proteins that escape sorting in control cells or in cells lacking MPR 46 and/or MPR 300 was strikingly similar, and oligosaccharides with two phosphomonoesters represented the major oligosaccharide species. We conclude from these results that the position of the position of the phosphate groups, the structure of the underlying oligosaccharide, and/or the polypeptide backbone of lysosomal proteins have major roles in determining the affinity to MPRs.