Kim K C, Rearick J I, Nettesheim P, Jetten A M
J Biol Chem. 1985 Apr 10;260(7):4021-7.
Hamster tracheal epithelial cells growing on type I collagen gel synthesize and secrete high molecular weight glycoconjugates which elute in the void volume upon Sepharose CL-4B column chromatography. The presence of any proteoglycans in this void volume material was ruled out based on both enzymatic analysis and behavior on DEAE-ion exchange chromatography. Based on the incorporation of radioactive precursors, followed by strong acid hydrolysis or neuraminidase digestion, the material was shown to contain sialic acid, fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sulfate. Complete susceptibility to papain digestion and reductive beta-elimination suggests that the material consists of O-linked glycoproteins. The identification of N-acetylgalactosaminitol in the beta-eliminated oligosaccharides confirms this notion. The molecular weight of the oligosaccharides following beta-elimination ranges from 4,000 to 15,000. We conclude that the high molecular weight glyconjugates produced by hamster tracheal epithelial cells in primary culture are mucous glycoproteins based on size, sensitivity to alkaline borohydride treatment, and monosaccharide composition. Further characterization of these mucous glycoproteins showed both size and charge microheterogeneity among molecules. Detailed structural analysis of oligosaccharides of these mucous glycoproteins is currently under way.
生长在I型胶原凝胶上的仓鼠气管上皮细胞合成并分泌高分子量糖缀合物，这些糖缀合物在Sepharose CL - 4B柱层析时于空体积中洗脱。基于酶分析和DEAE - 离子交换层析行为，排除了该空体积物质中存在任何蛋白聚糖的可能性。基于放射性前体的掺入，随后进行强酸水解或神经氨酸酶消化，结果表明该物质含有唾液酸、岩藻糖、半乳糖、N - 乙酰葡糖胺、N - 乙酰半乳糖胺和硫酸盐。对木瓜蛋白酶消化和还原性β - 消除完全敏感表明该物质由O - 连接糖蛋白组成。在β - 消除的寡糖中鉴定出N - 乙酰半乳糖醇证实了这一观点。β - 消除后寡糖的分子量范围为4000至15000。我们得出结论，原代培养的仓鼠气管上皮细胞产生的高分子量糖缀合物基于大小、对碱性硼氢化钠处理的敏感性和单糖组成，属于粘液糖蛋白。对这些粘液糖蛋白的进一步表征显示分子间存在大小和电荷微异质性。目前正在对这些粘液糖蛋白的寡糖进行详细的结构分析。
