Molecular cloning of a novel α2,3-sialyltransferase (ST3Gal VI) that sialylates type II lactosamine structures on glycoproteins and glycolipids
Molecular cloning of a novel α2,3-sialyltransferase (ST3Gal VI) that sialylates type II lactosamine structures on glycoproteins and glycolipids
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DOI：
10.1074/jbc.274.17.11479
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发表时间：
1999-04-23
影响因子：
4.8
通讯作者：
Furukawa, K
中科院分区：
文献类型：
--
作者：
Okajima, T;Fukumoto, S;Furukawa, K
基于表达序列标签的BLAST分析鉴定了人CMP-NeuAc：β-半乳糖苷α 2，3-唾液酸转移酶（ST）亚家族的新成员，命名为ST 3Gal VI，并且从人黑素瘤细胞系文库中分离了cDNA克隆。ST 3Gal VI的序列编码一个II型膜蛋白，具有2个氨基酸的胞质结构域，32个氨基酸的跨膜区，和一个大的催化结构域，具有297个氨基酸;并显示与先前克隆的ST 3Gal III，ST 3Gal IV和ST 3Gal V的同源性分别为34%，38%和33%。来自用表达载体中的ST 3Gal VI cDNA和与蛋白A的融合蛋白转染的L细胞的提取物显示出α 2，3-唾液酸转移酶对糖蛋白和糖脂上的Gal β 1，4GlcNAc结构的酶活性。与ST 3Gal III和ST 3Gal IV相反，该酶表现出有限的底物特异性，即它利用糖蛋白上的Gal β 1，4GlcNAc，和新乳糖四糖神经酰胺和新乳糖六糖神经酰胺，但不包括乳糖四糖神经酰胺、乳糖神经酰胺或去唾液酸-GM 1。因此，这些数据表明该酶参与唾液酸-副糖苷（唾液酸-Lewis X决定簇的前体）的合成。
A novel member of the human CMP-NeuAc:beta-galacto side alpha 2,3-sialyltransferase (ST) subfamily, designated ST3Gal VI, was identified based on BLAST analysis of expressed sequence tags, and a cDNA clone was isolated from a human melanoma line library. The sequence of ST3Gal VI encoded a type II membrane protein with 2 amino acids of cytoplasmic domain, 32 amino acids of transmembrane region, and a large catalytic domain with 297 amino acids; and showed homology to previously cloned ST3Gal III, ST3Gal IV, and ST3Gal V at 34, 38, and 33%, respectively. Extracts from L cells transfected with ST3Gal VI cDNA in a expression vector and a fusion protein with protein A showed an enzyme activity of alpha 2,3-sialyltransferase toward Gal beta 1,4GlcNAc structure on glycoproteins and glycolipids, In contrast to ST3Gal III and ST3Gal IV, this enzyme exhibited restricted substrate specificity, i.e. it utilized Gal beta 1,4GlcNAc on glycoproteins, and neolactotetraosylceramide and neolactohexaosylceramide, but not lactotetraosylceramide, lactosylceramide, or asialo-GM1. Consequently, these data indicated that this enzyme is involved in the synthesis of sialyl-paragloboside, a precursor of sialyl-Lewis X determinant.