Enzymatic basis for the structural changes of asparagine-linked sugar chains of membrane glycoproteins of baby hamster kidney cells induced by polyoma transformation.
Enzymatic basis for the structural changes of asparagine-linked sugar chains of membrane glycoproteins of baby hamster kidney cells induced by polyoma transformation.
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DOI：
10.1016/s0021-9258(18)89216-x
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发表时间：
1985-04
期刊：
影响因子：
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通讯作者：
K. Yamashita;Y. Tachibana;T. Ohkura;A. Kobata
中科院分区：
文献类型：
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作者：
K. Yamashita;Y. Tachibana;T. Ohkura;A. Kobata
先前的研究表明，在由多瘤病毒转化的幼仓鼠肾细胞的膜糖蛋白的复合型天冬酰胺连接的糖链中，GlcNAc β 1- 6 Man α 1-基团的富集伴随着GlcNAc β 1- 4 Man α 1-基团的减少。本文报道了这种化学变化的酶学基础。通过使用从患有各种外切糖苷酶缺乏症的患者的尿液中分离的寡糖，成功地分别测定了细胞匀浆中的β-N-乙酰葡糖胺转移酶。幼仓鼠肾细胞及其多瘤转化体均含有β-N-乙酰葡糖胺转移酶I、II、IV、V和VI，但不含有β-N-乙酰葡糖胺转移酶III。由每个β-N-乙酰葡糖胺转移酶（GnT）添加的β-N-乙酰葡糖胺残基如下所示。对两种细胞系中五种β-N-乙酰氨基葡萄糖基转移酶的比活性进行比较研究，发现多瘤细胞中β-N-乙酰氨基葡萄糖基转移酶V的值是正常细胞中的两倍，而两种细胞系中其他四种转移酶的值没有显著差异。因此，β-N-乙酰氨基葡萄糖转移酶V的增加可能是多瘤病毒转化的幼仓鼠肾细胞表面糖蛋白糖链变化的直接原因。
Previous studies indicated that enrichment of the GlcNAc beta 1—-6Man alpha 1—- group with concomitant decrease of the GlcNAc beta 1—-4Man alpha 1—- group occurs in the complex-type asparagine-linked sugar chains of the membrane glycoproteins of baby hamster kidney cells transformed by polyoma virus. The enzymatic basis of the chemical change is reported in this paper. By using oligosaccharides isolated from the urine of patients with a variety of exoglycosidase deficiencies, beta-N-acetylglucosaminyltransferases in the cell homogenate were successfully assayed separately. Both baby hamster kidney cells and their polyoma transformants contain beta-N-acetylglucosaminyltransferases I, II, IV, V, and VI, but not beta-N-acetylglucosaminyltransferase III. The beta-N-acetylglucosamine residue added by each beta-N-acetylglucosaminyltransferase (GnT) is shown below. (formula see text) Comparative studies of the specific activities of the five beta-N-acetylglucosaminyltransferases in the two cell lines revealed that the value of beta-N-acetylglucosaminyltransferase V in the polyoma transformant was twice of that in the normal cells, while those of the other four transferases in the two cell lines were not significantly different. Therefore the increase in beta-N-acetylglucosaminyltransferase V may be the direct cause of the changes found in the sugar chains of surface glycoproteins in baby hamster kidney cells transformed by polyoma virus.