Gain-of-function Chinese hamster ovary mutants LEC18 and LEC14 each express a novel N-acetylglucosaminyltransferase activity

J Biol Chem. 1998 Jun 5;273(23):14090-8. doi: 10.1074/jbc.273.23.14090.


LEC18 and LEC14 cells are gain-of-function glycosylation mutants isolated from Chinese hamster ovary cells for resistance to pea lectin. Structural studies have shown that LEC18 cells synthesize complex N-glycans with a GlcNAc residue linked at the O-6 position of the core GlcNAc (Raju, T. S., Ray, M. K., and Stanley, P. (1995) J. Biol. Chem. 270, 30294-30302), whereas LEC14 cells synthesize complex N-glycans with a GlcNAc residue linked at the O-2 position of the core beta-linked Man residue (Raju, T. S., and Stanley, P. (1996) J. Biol. Chem. 271, 7484-7493). Both modifications are novel and have not been reported in glycoproteins from any other source. We now show that, in both LEC18 and LEC14 cells, GlcNAc transfer is mediated by a distinct N-acetylglucosaminyltransferase (GlcNAc-T) activity. The LEC18 activity, termed GlcNAc-TVIII, transfers GlcNAc to GlcNAcbeta1-O-pNP and to a GlcNAc-terminating, biantennary, complex N-glycan, with or without a core fucose. By contrast, the LEC14 transferase, termed GlcNAc-TVII, does not have significant activity with simple acceptors, and transfers GlcNAc preferentially to a GlcNAc-terminating biantennary glycopeptide that contains a core fucose residue. The acceptor specificities and other biochemical properties of GlcNAc-TVII and GlcNAc-TVIII differ from previously characterized GlcNAc-transferases including GlcNAc-TIII, indicating that they represent new members of the mammalian GlcNAc-T group of transferases.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylglucosamine / metabolism
  • Adenosine Triphosphate / pharmacology
  • Animals
  • CHO Cells / enzymology*
  • Carbohydrate Conformation
  • Carbohydrate Sequence
  • Cricetinae
  • Glycopeptides / chemistry
  • Hydrogen-Ion Concentration
  • Kinetics
  • Manganese / pharmacology
  • Molecular Sequence Data
  • Mutation / genetics
  • N-Acetylglucosaminyltransferases / classification
  • N-Acetylglucosaminyltransferases / genetics*
  • Oligosaccharides / chemistry
  • Polysaccharides / chemistry
  • Substrate Specificity
  • beta-N-Acetylhexosaminidases / metabolism


  • Glycopeptides
  • Oligosaccharides
  • Polysaccharides
  • Manganese
  • Adenosine Triphosphate
  • N-Acetylglucosaminyltransferases
  • N-acetyllactosaminide beta-1,6-N-acetylglucosaminyltransferase
  • beta-N-Acetylhexosaminidases
  • Acetylglucosamine