Expression of catabolic pathway of asparagine-linked oligosaccharides on plasma membrane and apoptosis

1.远藤HS去糖基化靶糖蛋白（TGP）在人口腔附着上皮细胞中比在离体细胞中检测到更多，但在白细胞中没有检测到。凝胶内去糖基化法鉴定附着的上皮细胞中分子量为55K的蛋白为TGP55。MW在20K、50K和105 ~ 110K的蛋白也被指定为TGP20、TGP50和TGP105 ~ 110.2。TGP55和TGP50的鉴定分别纯化了TGP55和TGP50。n端氨基酸被认为是乙酰化的。脱乙酰TGP55的n端氨基酸序列与人细胞角蛋白13的内部氨基酸序列具有高度的同源性，但同源性搜索未发现具有相同n端氨基酸序列的蛋白。TGP50的n端氨基酸也被阻断。TGP50的n端和内部氨基酸序列与人类I型细胞角蛋白13具有高度同源性，表明TGP50是I型细胞角蛋白13或与其相似的蛋白。人I型细胞角蛋白13具有潜在的糖基化位点天冬酰胺。Endo HS被认为在该位点去除天冬酰胺连接的低聚糖，并参与上皮细胞的分化。利用TGP55单克隆抗体分析TGP55的免疫化学性质和细胞定位。每种抗体与TGP55等附着和离体上皮细胞的蛋白反应，附着和离体上皮细胞的蛋白种类不同。抗体对上皮细胞外围部分进行染色，表明TGP55定位于上皮细胞外围部分周围，剥离上皮细胞后定位发生变化。

1.Verification and specification of target glycoproteins deglycosylated by Endo HSTarget glycoprotein(TGP) deglycosylated by Endo HS was detected from attached epithelial cell in the human oral cavity more than detached cell, but not in leukocyte. The protein of molecular weight(MW) of 55K from the attached epithelial cell was specified as TGP55 by in-gel deglycosylation method. The proteins of MW of 20K, 50K and 105〜110K were also specified as TGP20, TGP50 and TGP105〜110.2.Identification of TGP55 and TGP50TGP55 and TGP50 were purified. The N-terminal amino acid was thought to be acetylated. The N-terminal amino acid sequence of deacetylated TGP55 showed high homology with the inner amino acid sequence of human cytokeratin 13, but no proteins having the same N-terminal amino acid sequence was not observed by homology search. The N-terminal amino acid of TGP50 was also blocked. The N-terminal and inner amino acid sequence of TGP50 showed high homology with those of human type I cytokerain 13, indicating that TGP50 is type I cytokeratin 13 or a similar protein to it. Human type I cytokeratin 13 has an asparagine of potential glycosylation site. Endo HS was thought to removing the asparagine-linked oligosaccharide at the site and taking part in the differentiation of the epithelial cell.3.Immunochemical properties and cellular localization of TGP55 analyzed using monoclonal antibodies against TGP55Three monoclonal antibodies against TGP55 were prepared. Each antibody reacted with TGP55 and other proteins of attached and detached epithelial cell, the kinds of proteins were different between attached and detached epithelial cell. The outskirts part of the epithelial cell was stained by the antibodies, indicating that TGP55 localizes around the outskirt part of the epithelial cell and the localization changes after peeling of the epithelial cell.