Cloning and Subcellular Localization of GalNAc Transferase

1.获得了人UDP-N-乙酰半乳糖胺同源物：多肽N-乙酰氨基半乳糖转移酶(GalNAc Transfer Ase)的cDNA克隆。结果：1.人GalNAc转移酶AcDNA序列与其牛同源基因高度同源，与最近报道的人类同工酶T1完全相同。根据获得的cDNA序列合成了23个残基的多肽，并成功地制备了抗GNT-1的鼠抗GNT-1单抗。GnT-1与胰腺、唾液腺、支气管腺和乳腺等外分泌器官的导管上皮细胞呈阳性反应。此外，GNT-1与唾液腺和胃的粘液细胞无反应。这些结果表明，导管上皮细胞和粘液细胞具有不同类型的GalNAc转移酶。值得注意的是，胃壁细胞和胰腺朗格汉斯岛的大量细胞对GNT-1表现出良好的反应性，提示这些细胞除了粘蛋白外，还能产生O-糖化蛋白。GNT-1免疫印迹显示GalNAc转移酶T1的表达不仅在器官类型和细胞类型之间存在差异，而且随着细胞分化的不同而不同。5.在上述结果的基础上，我们计划研究GalNAc转移酶T1在各种胃肠道疾病中的表达，并制备抗GalNAc转移酶T2的单抗

1. We have obtained a cDNA clone of the human homologue of the UDP-N-acctylgalactosamine : polypeptide N-acetylgalactosaminyltransferase (GalNAc transferase). AcDNA sequence for human GalNAc transferase showed high homology with its bovine homelogue and was identical to human isozyme Tlthat was recently reported.2. Twenty-three residues peptide was synthesized based on the obtained cDNA sequence and a mouse monoclonal antibody to the peptide (GNT-1) was successfully produced.3. GNT-1 reacted with ductal epithelial cells of the exocrine organs including pancreas, salivary gland, bronchial gland, and mammary gland. Oherewise, GNT-1 had no reactivity with mucus cells of salivary gland and stomach. These results suggest that ductal epithelial cells and mucus cells have different types of GalNAc transferase. It was noteworthy that parietal cells of stomach and a large number of cells in Langerhans islands of pancreas showed nice reactivity with GNT-1, suggesting these cells produce O-glycosylated protein except for mucin.4. Western immunoblotting with GNT-1 showed that the expression of GalNAc transferase T1 varies not only among organ types and cell type, but also according to cell differentiation.5.Based on the results deceribed above, we plan to study the expression of GalNAc transferase T1 in various kinds of gastrointstinal disease and produce a monoclonal antibody to GalNAc transferase T2