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J Biol Chem. 2013 Jul 26;288(30):21850-60. doi: 10.1074/jbc.M113.460543. Epub 2013 Jun 13.

UDP-N-acetylglucosamine transporter (SLC35A3) regulates biosynthesis of highly branched N-glycans and keratan sulfate.

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Laboratory of Biochemistry, Faculty of Biotechnology, University of Wrocław, 2 Tamka Street, 50-137 Wrocław, Poland.


SLC35A3 is considered the main UDP-N-acetylglucosamine transporter (NGT) in mammals. Detailed analysis of NGT is restricted because mammalian mutant cells defective in this activity have not been isolated. Therefore, using the siRNA approach, we developed and characterized several NGT-deficient mammalian cell lines. CHO, CHO-Lec8, and HeLa cells deficient in NGT activity displayed a decrease in the amount of highly branched tri- and tetraantennary N-glycans, whereas monoantennary and diantennary ones remained unchanged or even were accumulated. Silencing the expression of NGT in Madin-Darby canine kidney II cells resulted in a dramatic decrease in the keratan sulfate content, whereas no changes in biosynthesis of heparan sulfate were observed. We also demonstrated for the first time close proximity between NGT and mannosyl (α-1,6-)-glycoprotein β-1,6-N-acetylglucosaminyltransferase (Mgat5) in the Golgi membrane. We conclude that NGT may be important for the biosynthesis of highly branched, multiantennary complex N-glycans and keratan sulfate. We hypothesize that NGT may specifically supply β-1,3-N-acetylglucosaminyl-transferase 7 (β3GnT7), Mgat5, and possibly mannosyl (α-1,3-)-glycoprotein β-1,4-N-acetylglucosaminyltransferase (Mgat4) with UDP-GlcNAc.


Branched N-Glycans; Glycosylation; Glycosyltransferases; Golgi; Keratan; Proteoglycan; UDP-N-Acetylglucosamine Transporter

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