MAMMALIAN GLYCOSYLTRANSFERASES PREFER GLYCOSYL PHOSPHORYL DOLICHOLS RATHER THAN GLYCOSYL PHOSPHORYL POLYPRENOLS AS SUBSTRATES FOR OLIGOSACCHARYL SYNTHESIS
MAMMALIAN GLYCOSYLTRANSFERASES PREFER GLYCOSYL PHOSPHORYL DOLICHOLS RATHER THAN GLYCOSYL PHOSPHORYL POLYPRENOLS AS SUBSTRATES FOR OLIGOSACCHARYL SYNTHESIS
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DOI：
10.1006/abbi.1994.1070
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发表时间：
1994-02-01
影响因子：
3.9
通讯作者：
ELBEIN, AD
中科院分区：
文献类型：
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作者：
D'SOUZA-SCHOREY, C;MCLACHLAN, KR;ELBEIN, AD
我们研究了聚戊烯基- p -甘露糖和聚戊烯醇- p -葡萄糖分别作为多基- p -甘露糖：Man(5)(GlcNAc)(2)- pp -多醇甘露糖基转移酶和多基- p -葡萄糖：Man(9)(GlcNAc)(2)- pp -多醇糖基转移酶的供体底物的有效性。聚戊二醇部分与醇的不同之处在于分子末端异戊二烯单元的不饱和。根据反应动力学，我们发现两种糖基转移酶使用聚戊烯醇- p单糖比使用聚戊烯醇- p单糖具有更高的表观K(m)s和更低的表观V(max)s，聚戊烯醇- p糖与使用聚戊烯醇- p单糖形成的产物相同，表明聚戊烯醇底物可以被糖基转移酶在体外利用。结果还表明，聚丙烯酰p糖和聚丙烯酰p糖在酶上竞争相同的结合位点。这些发现对于理解中国仓鼠卵巢细胞突变体Lec9互补组的糖基化表型具有重要意义，该突变体缺乏将聚戊二醇转化为乙醇的能力。(C) 1994学术出版社，Inc.
We have studied the effectiveness of polyprenyl-P-mannose and polyprenol-P-glucose as donor substrates for the dolichyl-P-mannose:Man(5)(GlcNAc)(2)-PP-dolichol mannosyltransferase and the dolichyl-P-glucose: Man(9)(GlcNAc)(2)-PP-dolichol glucosyltransferase, respectively. The polyprenol moiety differs from dolichol only in the unsaturation of the terminal isoprene unit of the molecule. Based on the kinetics of the reactions, we have found that both glycosyltransferases have higher apparent K(m)s and lower apparent V(max)s using polyprenyl-P-monosaccharides as substrates rather than the dolichyl-P-monosaccharides The products formed with the polyprenyl-P-sugars were the same as those formed by the dolichol-linked sugars, indicating that the polyprenol substrates could be utilized by the glycosyltransferases in vitro. The results also indicate that the dolichyl-P-sugars and the polyprenyl-P-sugars compete for the same binding site on the enzyme. These findings are significant in terms of understanding the glycosylation phenotypes of Chinese hamster ovary cell mutants of the Lec9 complementation group, which lack the ability to convert polyprenol into dolichol. (C) 1994 Academic Press, Inc.