A Novel Human β1,3-N-Acetylgalactosaminyltransferase That Synthesizes a Unique Carbohydrate Structure, GalNAcβ1-3GlcNAc
| Autor: | Katsuya Fujimura, Norihiro Kikuchi, Takashi Sato, Toshiaki Noce, Toru Hiruma, Hisashi Narimatsu, Kouichi Tachibana, Hiroshi Nakanishi, Yeon-Dae Kwon, Aya Nakamura, Kayo Okamura, Akira Togayachi, Masanori Gotoh, Yasuko Ishizuka |
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| Rok vydání: | 2004 |
| Předmět: |
Molecular Sequence Data
Oligosaccharides Biology Biochemistry Substrate Specificity Mice Glycolipid Glycosyltransferase Animals Humans Amino Acid Sequence RNA Messenger Nuclear Magnetic Resonance Biomolecular Molecular Biology Gene In Situ Hybridization Phylogeny chemistry.chemical_classification Expressed sequence tag Base Sequence HEK 293 cells Computational Biology Cell Biology Molecular biology Fetuin Amino acid Open reading frame Carbohydrate Sequence chemistry biology.protein N-Acetylgalactosaminyltransferases Protons |
| Zdroj: | Journal of Biological Chemistry. 279:14087-14095 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m310614200 |
| Popis: | We found, using a BLAST search, a novel human gene (GenBank trade mark accession number BC029564) that possesses beta3-glycosyltransferase motifs. The full-length open reading frame consists of 500 amino acids and encodes a typical type II membrane protein. This enzyme has a domain containing beta1,3-glycosyltransferase motifs, which are widely conserved in the beta1,3-galactosyltransferase and beta1,3-N-acetylglucosaminyltransferase families. The putative catalytic domain was expressed in human embryonic kidney 293T cells as a soluble protein. Its N-acetylgalactosaminyltransferase activity was observed when N-acetylglucosamine (GlcNAc) beta1-O-benzyl was used as an acceptor substrate. The enzyme product was determined to have a beta1,3-linkage by NMR spectroscopic analysis, and was therefore named beta1,3-N-acetylgalactosaminyltransferase-II (beta3GalNAc-T2). The acceptor substrate specificity of beta3GalNAc-T2 was examined using various oligosaccharide substrates. Galbeta1-3(GlcNAcbeta1-6)GalNAcalpha1-O-para-nitrophenyl (core 2-pNP) was the best acceptor substrate for beta3GalNAc-T2, followed by GlcNAcbeta1-4GlcNAcbeta1-O-benzyl, and GlcNAcbeta1-6GalNAcalpha1-O-para-nitrophenyl (core 6-pNP), among the tested oligosaccharide substrates. Quantitative real time PCR analysis revealed that the beta3Gal-NAc-T2 transcripts was restricted in its distribution mainly to the testis, adipose tissue, skeletal muscle, and ovary. Its putative orthologous gene, mbeta3GalNAc-T2, was also found in a data base of mouse expressed sequence tags. In situ hybridization analysis with mouse testis showed that the transcripts are expressed in germ line cells. beta3GalNAc-T2 efficiently transferred GalNAc to N-glycans of fetal calf fetuin, which was treated with neuraminidase and beta-galactosidase. However, it showed no activity toward any glycolipid examined. Although the GalNAcbeta1-3GlcNAcbeta1-R structure has not been reported in humans or other mammals, we have discovered a novel human glycosyltransferase producing this structure on N- and O-glycans. |
| Databáze: | OpenAIRE |
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