UDP-GlcNAc concentration is an important factor in the biosynthesis of beta1,6-branched oligosaccharides: regulation based on the kinetic properties of N-acetylglucosaminyltransferase V.
UDP-GlcNAc concentration is an important factor in the biosynthesis of beta1,6-branched oligosaccharides: regulation based on the kinetic properties of N-acetylglucosaminyltransferase V.
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DOI：
10.1093/glycob/12.2.119
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发表时间：
2002-02
期刊：
影响因子：
4.3
通讯作者：
K. Sasai;Y. Ikeda;T. Fujii;T. Tsuda;N. Taniguchi
中科院分区：
文献类型：
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作者：
K. Sasai;Y. Ikeda;T. Fujii;T. Tsuda;N. Taniguchi
利用杆状病毒-昆虫细胞系统表达了人β，6- n -乙酰氨基葡萄糖转移酶V (GnT-V)，并对重组酶进行了动力学表征。获得的数据用于建立对供体核苷酸糖的底物特异性的动力学基础，并且还揭示了供体的K(m)值远高于其他GlcNAc转移酶，这些转移酶的动力学性质已被报道。因为这个异常高的K(m)表明GnT-V在远离饱和的条件下是生理上存在的，这似乎表明由GnT-V形成的β a1,6支低聚糖的产生可以通过供体的浓度来调节，UDP-GlcNAc，以及酶的表达水平。当表达高水平GnT-V的B16黑色素瘤细胞与GlcNAc孵养时，通过凝集素印迹分析判断，β a1,6支低聚糖水平升高，同时细胞内UDP-GlcNAc升高。这些发现表明，UDP-GlcNAc的水平可能是产生β a1,6支低聚糖的关键因素，例如，被认为与肿瘤进展和转移密切相关的肿瘤细胞。
Human beta1,6-N-acetylglucosaminyltransferase V (GnT-V) was expressed by baculovirus-insect cell system, and the purified recombinant enzyme was kinetically characterized. The data obtained were used to establish the kinetic basis of the substrate specificity toward donor nucleotide sugars, and also revealed that K(m) values for the donors are much higher compared to those of other GlcNAc transferases, the kinetic properties of which have been reported. Because this exceptionally higher K(m) suggests that GnT-V is physiologically present at far from saturated conditions, it would appear that the production of beta1,6-branched oligosaccharide, which is formed by GnT-V, could be regulated in vivo by the concentration of the donor, UDP-GlcNAc, as well as the expression levels of the enzyme. When B16 melanoma cells, which express high levels of GnT-V, were incubated with GlcNAc, the beta1,6-branched oligosaccharide levels were increased, as judged by a lectin blot analysis, in conjunction with an increase in intracellular UDP-GlcNAc. These findings suggest that the level of UDP-GlcNAc can be a critical factor in the production of beta1,6-branched oligosaccharides, for example, by tumor cells, which have been thought to be closely associated with tumor progression and metastasis.