Merlie J P, Sebbane R, Tzartos S, Lindstrom J
J Biol Chem. 1982 Mar 10;257(5):2694-701.
We have characterized the oligosaccharide chains of the alpha subunit of acetylcholine receptor of the clonal mouse muscle cell line BC3H-1 by their sensitivity to end-beta-N-acetylglucosaminidase H and by comparison of the native glycosylated polypeptide with the nonglycosylated form made in tunicamycin-treated cells. These studies indicate that the native alpha subunit has a single N-asparagine-linked oligosaccharide chain of the "high mannose" or "simple" type. Furthermore, these results considered in light of our previous characterization of the alpha subunit synthesized in vitro suggest that the alpha subunit contains no "complex"-type N-linked oligosaccharide chains. We have investigated the role of glycosylation in the biogenesis of the acetylcholine receptor. Receptor biogenesis in normal cells involves the assembly of newly synthesized alpha subunits into a form active for binding alpha-bungarotoxin. This process is only 30% efficient and is complete by 30 min postsynthesis. When glycosylation is inhibited by tunicamycin, alpha subunit synthesis is inhibited only slightly but assembly into an alpha-bungarotoxin binding species is reduced dramatically.
我们通过研究克隆小鼠肌肉细胞系BC3H-1乙酰胆碱受体α亚基的寡糖链对β-N-乙酰氨基葡萄糖苷酶H的敏感性，并将天然糖基化多肽与衣霉素处理细胞中产生的非糖基化形式进行比较，对其进行了表征。这些研究表明，天然α亚基具有一条“高甘露糖”或“简单”类型的单一N-天冬酰胺连接的寡糖链。此外，根据我们之前对体外合成的α亚基的表征，这些结果表明α亚基不包含“复杂”类型的N-连接寡糖链。我们研究了糖基化在乙酰胆碱受体生物合成中的作用。正常细胞中的受体生物合成涉及将新合成的α亚基组装成一种对结合α-银环蛇毒素有活性的形式。这个过程的效率只有30%，并且在合成后30分钟内完成。当用衣霉素抑制糖基化时，α亚基的合成仅略有抑制，但组装成α-银环蛇毒素结合物种的过程则显著减少。
