The beta 1,3-galactosyltransferase beta 3GalT-V is a stage-specific embryonic antigen-3 (SSEA-3) synthase.
We have previously reported the molecular cloning of beta1, 3-galactosyltransferase-V (beta3GalT-V), which catalyzes the transfer of Gal to GlcNAc-based acceptors with a preference for the core3 O-linked glycan GlcNAc(beta1,3)GalNAc structure. Further characterization indicated that the recombinant beta3GalT-V enzyme expressed in Sf9 insect cells also utilized the glycolipid Lc3Cer as an efficient acceptor. Surprisingly, we also found that beta3GalT-V catalyzes the transfer of Gal to the terminal GalNAc unit of the globoside Gb4, thereby synthesizing the glycolipid Gb5, also known as the stage-specific embryonic antigen-3 (SSEA-3). The SSEA-3 synthase activity of beta3GalT-V was confirmed in vivo by stable expression of the human beta3GalT-V gene in F9 mouse teratocarcinoma cells, as detected with the monoclonal antibody MC-631 by flow cytometry analysis and immunostaining of extracted glycolipids. The biological relation between SSEA-3 formation and beta3GalT-V was further documented by showing that F9 cells treated with the differentiation-inducing agent retinoic acid induced the expression of both the SSEA-3 epitope and the endogenous mouse beta3GalT-V gene. This study represents the first example of a glycosyltransferase, which utilizes two kinds of sugar acceptor substrates without requiring any additional modifier molecule.
Zhou
D
D
Institute of Physiology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Henion
T R
TR
Jungalwala
F B
FB
Berger
E G
EG
Hennet
T
T
D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate; D001483:Base Sequence; D017931:DNA Primers; D005700:Galactosyltransferases / Q000235:genetics / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D055746:Stage-Specific Embryonic Antigens; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D015295:Antigens, Tumor-Associated, Carbohydrate; D017931:DNA Primers; D006028:Glycosphingolipids; D055746:Stage-Specific Embryonic Antigens; C052924:stage-specific embryonic antigen-3; D005700:Galactosyltransferases; C120745:UDP-galactose N-acetylglucosaminyl-1-3-N-acetylgalactosamine beta-1,3-galactosyltransferase