Molecular cloning and characterization of human GnT-IX, a novel beta1,6-N-acetylglucosaminyltransferase that is specifically expressed in the brain

J Biol Chem. 2003 Oct 31;278(44):43102-9. doi: 10.1074/jbc.M308255200. Epub 2003 Aug 26.


A novel beta1,6-N-acetylglucosaminyltransferase (beta1, 6GnT) cDNA was identified by a BLAST search using the amino acid sequence of human GnT-V as a query. The full-length sequence was determined by a combination of 5'-rapid amplification of cDNA end analysis and a further data base search. The open reading frame encodes a 792 amino acid protein with a type II membrane protein structure typical of glycosyltransferases. The entire sequence identity to human GnT-V is 42%. When pyridylaminated (PA) agalacto biantennary N-linked oligosaccharide was used as an acceptor substrate, the recombinant enzyme generated a novel product other than the expected GnT-V product, (GlcNAcbeta1,2-Manalpha1,3-)[GlcNAcbeta1,2-(GlcNAcbeta1,6-)Manalpha1,6-]Manbeta1,4-GlcNAcbeta1,4-GlcNAc-PA. This new product was identified as [GlcNAcbeta1,2-(GlcNAcbeta1,6-)Manalpha1,3-][Glc-NAcbeta1,2-(GlcNAcbeta1,6-)Manalpha1,6-]Manbeta1,4-GlcNAcbeta1,4-GlcNAc-PA by mass spectrometry and 1H NMR. Namely, the new GnT (designated as GnT-IX) has beta1,6GnT activity not only to the alpha1,6-linked mannose arm but also to the alpha1,3-linked mannose arm of N-glycan, forming a unique structure that has not been reported to date. Northern blot analysis showed that the GnT-IX gene is exclusively expressed in the brain, whereas the GnT-V gene is expressed ubiquitously. These results suggest that GnT-IX is responsible for the synthesis of a unique oligosaccharide structure in the brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Northern
  • Blotting, Western
  • Brain / enzymology*
  • Cell Line
  • Chromatography, High Pressure Liquid
  • Cloning, Molecular
  • DNA / metabolism
  • DNA, Complementary / metabolism
  • Genetic Vectors
  • Glycosylation
  • Humans
  • Ligands
  • Magnetic Resonance Spectroscopy
  • Models, Chemical
  • Molecular Sequence Data
  • N-Acetylglucosaminyltransferases / biosynthesis*
  • N-Acetylglucosaminyltransferases / chemistry*
  • N-Acetylglucosaminyltransferases / genetics*
  • Nerve Tissue Proteins / biosynthesis*
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / genetics*
  • Neurons / metabolism
  • Oligosaccharides / metabolism
  • Open Reading Frames
  • Precipitin Tests
  • RNA, Messenger / metabolism
  • Sequence Homology, Amino Acid
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Tissue Distribution


  • DNA, Complementary
  • Ligands
  • Nerve Tissue Proteins
  • Oligosaccharides
  • RNA, Messenger
  • DNA
  • MGAT5B protein, human
  • N-Acetylglucosaminyltransferases
  • alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase

Associated data

  • GENBANK/AB109185