Increased sialylation of complex glycopeptides during differentiation of mouse embryonal carcinoma cells.
Increased sialylation of complex glycopeptides during differentiation of mouse embryonal carcinoma cells.
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小鼠胚胎癌细胞分化过程中复杂糖肽的唾液酸化增加。
DOI：
10.1111/j.1432-0436.1985.tb00293.x
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Warren,L
中科院分区：
文献类型：
--
作者：
Cossu,G;Cortesi,E;Warren,L
高分子量，天冬酰胺连接的糖肽-乳糖胺聚糖-是F9细胞合成的蛋白质结合碳水化合物的主要类别；这些细胞只合成少量较小的糖肽。相比之下，F9ACC19，一种源自F9细胞的内胚层细胞系，只合成少量的乳糖胺聚糖和高比例的较小的糖肽。对F9ACC19细胞中的小糖肽进行生化分析发现，它们比F9细胞中的小糖肽更大，与刀豆蛋白A Sepharose的结合效率较低，并且含有更多的唾液酸。这两种细胞类型都含有一小部分高甘露糖糖肽。当由F9ACC19细胞合成时，水疱性口炎病毒的糖肽与由F9细胞合成的糖肽相比，显示出高水平的唾液化，F9细胞很少或没有唾液酸残基；这表明观察到的总糖肽的差异反映了细胞糖基化机制的差异。与这一观察结果一致的是，使用多种受体的体外唾液转移酶活性在F9ACC19细胞中明显高于F9细胞，而半乳糖转移酶活性在F9ACC19细胞中降低了几倍。这些数据支持了这样的假设，即在内胚层分化的F9ACC19细胞中，唾液基转移酶活性的增加可能会阻断糖肽末端的半乳糖残基，从而抑制这些细胞中乳胺聚糖的合成。
High‐molecular‐weight, asparagine‐linked glycopeptides – the lactosaminoglycans – are the major class of protein‐bound carbohydrates synthesized by F9 cells; these cells synthesize only minor amounts of smaller glycopeptides. In contrast, F9ACC19, an endodermal cell line derived from F9 cells, synthesizes only minor amounts of lactosaminoglycans and a high proportion of smaller glycopeptides. Biochemical analysis of the small glycopeptides from F9ACC19 cells revealed that they are larger, bind less efficiently to concanavalin‐A Sepharose and contain more sialic acid than their counterparts from F9 cells. Both cell types contain a small proportion of high‐mannose glycopeptides. When synthesized by F9ACC19 cells, the glycopeptides of vesicular stomatitis virus show a high level of sialylation as compared to those synthesized by F9 cells, where few or no sialic‐acid residues are present; this shows that the differences observed in total glycopeptides reflect differences in the glycosylation machinery of the cells. Consistent with this observation, sialyltransferase activity in vitro using a variety of acceptors was found to be markedly higher in F9ACC19 than in F9 cells, while galactosyltransferase activity was reduced several fold in F9ACC19 cells. These data support the hypothesis that the increased sialyltransferase activity in endodermal differentiated F9ACC19 cells may block the terminal galactose residue of glycopeptides, thereby inhibiting the synthesis of lactosaminoglycans in these cells.