Synthesis of the glycosaminoglycan-protein linkage tetraosyl peptide moieties of betaglycan, which serve as a hexosamine acceptor for enzymatic glycosyl transfer |
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Authors: | Jun-ichi Tamura Tomomi Nakamura-Yamamoto Shuji Mizumoto Kazuyuki Sugahara |
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Affiliation: | a Department of Regional Environment, Faculty of Regional Sciences, Tottori University, Tottori 680-8551, Japan b Laboratory of Proteoglycan Signaling and Therapeutics, Frontier Research Center for Post-Genomic Science and Technology, Faculty of Advanced Life Science, Hokkaido University Graduate School of Life Science, Sapporo 001-0021, Japan |
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Abstract: | Betaglycan, also known as TGF-β type III receptor, is a membrane-anchored proteoglycan, which has two glycosaminoglycan (GAG) attachment sites (López-Casillas, F.; Payne, H. M.; Andres, J. L.; Massagué, J. J.Cell Biol.1994, 124, 557-568). Chondroitin sulfate (CS) or heparan sulfate (HS) can attach to the first site, Ser535, whereas only CS attaches to the second, Ser546. Although the mechanism behind the assembly of CS and HS is not fully understood, it has been reported that the assembly of HS requires not only a cluster of acidic residues but also hydrophobic residues located near the Ser-Gly attachment sites (Esko, J. D. Zhang, L. Curr. Opin. Struct. Biol.1996, 6, 663-670). To further understand the effects of amino acids close to the Ser residues of the GAG-attachment sites on the glycosyltransferases, two tetraosyl peptides derived from the CS attachment sites of betaglycan, GlcA-Gal-Gal-Xyl-SerGlyAspAsnGly (1) and GlcA-Gal-Gal-Xyl-SerGlyAspAsnGlyPheProGly (2), were synthesized, and used as donor substrates for β1,4-N-acetylgalactosaminyltransferase-I (β4GalNAcT-I) and α1,4-N-acetylglucosaminyltransferase-I (α4GlcNAcT-I). Both the chemically synthesized linkage region tetrasaccharides were far better acceptors for β4GalNAcT-I than for α4GlcNAcT-I in vitro, although they also showed appreciable acceptor activity for α4GlcNAcT-I. |
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Keywords: | Chondroitin sulfate Heparan sulfate Glycoconjugate synthesis Glycosyl transfer N-Acetylgalactosaminyltransferase-I α1,4-N-Acetylglucosaminyltransferase-I |
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