van Beurden-Lamers W M, Spee-Brand R, Dekker J, Strous G J
Department of Cell Biology, State University of Utrecht School of Medicine, The Netherlands.
Biochim Biophys Acta. 1989 Mar 24;990(3):232-9. doi: 10.1016/s0304-4165(89)80039-x.
The synthesis of mucus glycoprotein in rat stomach was studied in stomach segments, which were pulse-labelled with both [3H]galactose and [35S]sulphate and chased for various times. The radioactive glycoproteins were analyzed by CsCl centrifugation and by agarose gel electrophoresis. After a pulse-labelling for 15 min with [3H]galactose, a possible intermediate with an Mr of 200,000 and a buoyant density of 1.60 g/ml could be demonstrated. Following chase periods of 1 and 4 h, [3H]galactose and [35S]sulphate were present in glycoproteins with a mean buoyant density of 1.50 g/ml. This is clearly different from the main density of glycoproteins isolated from mucosal scrapings (1.46 g/ml). Another difference is the high electrophoretic mobility on gel electrophoretic analysis of newly synthesized glycoproteins compared to that of the major portion of the glycoproteins from mucosal scrapings. When sulphation of glycoproteins was inhibited by sodium chlorate, electrophoretic mobility and buoyant density both decreased. Sodium chlorate had no effect on glycoprotein synthesis nor on glycoprotein secretion. We conclude from our data that the heterogeneity in electrophoretic mobility and buoyant density can be attributed to a different degree of sulphation of the same glycoprotein.
在大鼠胃的各个节段中研究了黏液糖蛋白的合成，这些节段用[³H]半乳糖和[³⁵S]硫酸盐进行脉冲标记，并追踪不同时间。通过CsCl离心和琼脂糖凝胶电泳分析放射性糖蛋白。用[³H]半乳糖脉冲标记15分钟后，可证明存在一种可能的中间体，其相对分子质量为200,000，浮力密度为1.60 g/ml。在追踪1小时和4小时后，[³H]半乳糖和[³⁵S]硫酸盐存在于平均浮力密度为1.50 g/ml的糖蛋白中。这与从黏膜刮片中分离的糖蛋白的主要密度（1.46 g/ml）明显不同。另一个差异是，与黏膜刮片中大部分糖蛋白相比，新合成的糖蛋白在凝胶电泳分析中的电泳迁移率较高。当用氯酸钠抑制糖蛋白的硫酸化时，电泳迁移率和浮力密度均降低。氯酸钠对糖蛋白合成和糖蛋白分泌均无影响。我们从数据中得出结论，电泳迁移率和浮力密度的异质性可归因于同一糖蛋白硫酸化程度的不同。
