Cloning of a human UDP-galactose:2-acetamido-2-deoxy-D-glucose 3beta-galactosyltransferase catalyzing the formation of type 1 chains

J Biol Chem. 1998 Jan 2;273(1):433-40. doi: 10.1074/jbc.273.1.433.


Biochemical evidence suggests that the galactosyltransferase activity synthesizing type 1 carbohydrate chains is separate from the well characterized enzyme that is responsible for the synthesis of type 2 chains. This was recently confirmed by the cloning, from melanoma cells, of an enzyme capable of synthesizing type 1 chains, which was shown to have no homology to other galactosyltransferases. We report here the molecular cloning and functional expression of a second human beta3-galactosyltransferase distinct from the melanoma enzyme. The new beta3-galactosyltransferase has homology to the melanoma enzyme in the putative catalytic domain, but has longer cytoplasmic and stem regions and a carboxyl-terminal extension. Northern blots showed that the new gene is present primarily in brain and heart. When transfected into mammalian cells, this gene directs the synthesis of type 1 chains as determined by a monoclonal antibody specific for sialyl Lewisa. A soluble version of the cloned enzyme was expressed in insect cells and purified. The soluble enzyme readily catalyzes the transfer of galactose to GlcNAc to form Gal(beta1-3)GlcNAc. It also has a minor but distinct transfer activity toward Gal, LacNAc, and lactose, but is inactive toward GalNAc.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Brain / enzymology
  • CHO Cells
  • Carbohydrate Metabolism*
  • Carbohydrates / biosynthesis
  • Catalysis
  • Cloning, Molecular
  • Cricetinae
  • DNA, Complementary
  • Galactosyltransferases / genetics*
  • Galactosyltransferases / metabolism
  • Humans
  • Kinetics
  • Melanoma / enzymology
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Staphylococcal Protein A / genetics
  • Staphylococcal Protein A / metabolism


  • Carbohydrates
  • DNA, Complementary
  • Recombinant Fusion Proteins
  • Staphylococcal Protein A
  • Galactosyltransferases
  • UDP-galactose 2-acetamido-2-deoxy-D-glucose 3-galactosyltransferase

Associated data

  • GENBANK/Y15014