Breloy Isabelle, Schwientek Tilo, Althoff Deborah, Holz Marvin, Koppen Tim, Krupa Angelika, Hanisch Franz-Georg
Institute for Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann Str. 52, Cologne 50931, Germany.
Octapharma Biopharmaceuticals GmbH, Im Neuenheimer Feld 590, Heidelberg 69220, Germany.
Biomolecules. 2016 Jan 6;6(1):8. doi: 10.3390/biom6010008.
The Drosophila melanogaster glucuronyltransferases dGlcAT-S and dGlcAT-P were reported to be expressed ubiquitously and results of in vitro activity assays indicate a functional redundancy. We analyzed both transferases in vivo and in vitro and could show significant differences in their activity towards N-and O-glycoproteins in vivo. While GlcAT-P is able to use N-linked N-acetyllactosamine chains and the O-linked T-antigen as a substrate to form non-sulfated HNK1- (GlcAβ1-3Galβ1-4GlcNAcβ1-) and glucuronyl-T-antigens in vivo, GlcAT-S adds glucuronic acid only to N-linked chains, thereby synthesizing only the non-sulfated HNK1-antigen.
据报道，果蝇的葡萄糖醛酸转移酶dGlcAT-S和dGlcAT-P在体内广泛表达，体外活性测定结果表明它们具有功能冗余性。我们在体内和体外对这两种转移酶进行了分析，结果显示它们在体内对N-糖蛋白和O-糖蛋白的活性存在显著差异。虽然GlcAT-P能够利用N-连接的N-乙酰乳糖胺链和O-连接的T抗原作为底物，在体内形成非硫酸化的HNK1-（GlcAβ1-3Galβ1-4GlcNAcβ1-）和葡萄糖醛酸基-T抗原，但GlcAT-S仅将葡萄糖醛酸添加到N-连接链上，因此仅合成非硫酸化的HNK1抗原。
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