Shitara N, McKeever P E, Smith B H, Pleasants R E, Banks M A, Kornblith P L
J Neurochem. 1982 Oct;39(4):948-53. doi: 10.1111/j.1471-4159.1982.tb11481.x.
With [3H]fucose as a marker, C6 glioma cells in culture released an 85,000 molecular weight molecule into the medium as the major extracellular glycoprotein. The quantity and extracellular/cytoplasmic ratio of this glycoprotein suggest that its cellular processing is different from that of five other released glycoproteins of molecular weights 55,000, 115,000, 130,000, 150,000, and 170,000. Nearly 40% of newly synthesized glycoproteins in the cells was released into the culture medium. Major glycoproteins retained by the cells migrated electrophoretically to molecular weight positions of 82,000, 110,000, 120,000, 140,000, and 160,000, and approximately one-third of these returned glycoproteins were labile to trypsinization. Both synthesis and release of these macromolecules were inhibited more than 95% with cycloheximide treatment, demonstrating that nearly all fucosylation was linked to protein synthesis. Since 40% of all glycoproteins was released under conditions of more than 99% cellular viability, it is likely that these extracellular glycoproteins are physiological products of membrane turnover and secretion, but not of cell lysis. The results provide a basis for the further study of glial differentiation and of shed glioma antigens.
以[3H]岩藻糖作为标记物，培养的C6胶质瘤细胞向培养基中释放出一种分子量为85,000的分子，作为主要的细胞外糖蛋白。这种糖蛋白的数量和细胞外/细胞质比例表明，其细胞加工过程与其他五种分子量分别为55,000、115,000、130,000、150,000和170,000的释放型糖蛋白不同。细胞中新合成的糖蛋白近40%释放到培养基中。细胞保留的主要糖蛋白在电泳中迁移到分子量为82,000、110,000、120,000、140,000和160,000的位置，并且这些回收的糖蛋白中约三分之一对胰蛋白酶处理不稳定。用环己酰亚胺处理后，这些大分子的合成和释放均受到超过95%的抑制，表明几乎所有岩藻糖基化都与蛋白质合成有关。由于在细胞存活率超过99%的条件下，所有糖蛋白中有40%被释放，因此这些细胞外糖蛋白很可能是膜周转和分泌的生理产物，而不是细胞裂解的产物。这些结果为进一步研究胶质细胞分化和脱落的胶质瘤抗原提供了基础。
