Sulfation of N-acetylglucosamine by chondroitin 6-sulfotransferase 2 (GST-5).
Based on sequence homology with a previously cloned human GlcNAc 6-O-sulfotransferase, we have identified an open reading frame (ORF) encoding a novel member of the Gal/GalNAc/GlcNAc 6-O-sulfotransferase (GST) family termed GST-5 on the human X chromosome (band Xp11). GST-5 has recently been characterized as a novel GalNAc 6-O-sulfotransferase termed chondroitin 6-sulfotransferase-2 (Kitagawa, H., Fujita, M., Itio, N., and Sugahara K. (2000) J. Biol. Chem. 275, 21075-21080). We have coexpressed a human GST-5 cDNA with a GlyCAM-1/IgG fusion protein in COS-7 cells and observed four-fold enhanced [(35)S]sulfate incorporation into this mucin acceptor. All mucin-associated [(35)S]sulfate was incorporated as GlcNAc-6-sulfate or Galbeta1-->4GlcNAc-6-sulfate. GST-5 was also expressed in soluble epitope-tagged form and found to catalyze 6-O-sulfation of GlcNAc residues in synthetic acceptor structures. In particular, GST-5 was found to catalyze 6-O-sulfation of beta-benzyl GlcNAc but not alpha- or beta-benzyl GalNAc. In the mouse genome we have found a homologous ORF that predicts a novel murine GlcNAc 6-O-sulfotransferase with 88% identity to the human enzyme. This gene was mapped to mouse chromosome X at band XA3.1-3.2. GST-5 is the newest member of an emerging family of carbohydrate 6-O-sulfotransferases that includes chondroitin 6-sulfotransferase (GST-0), keratan-sulfate galactose 6-O-sulfotransferase (GST-1), the ubiquitously expressed GlcNAc 6-O-sulfotransferase (GST-2), high endothelial cell GlcNAc 6-O-sulfotransferase (GST-3), and intestinal GlcNAc 6-O-sulfotransferase (GST-4).
Bhakta
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S
Department of Respiratory Diseases, Roche Bioscience, Palo Alto, California 94304, USA.
Bartes
A
A
Bowman
K G
KG
Kao
W M
WM
Polsky
I
I
Lee
J K
JK
Cook
B N
BN
Bruehl
R E
RE
Rosen
S D
SD
Bertozzi
C R
CR
Hemmerich
S
S
D000117:Acetylglucosamine / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002384:Catalysis; D002874:Chromosome Mapping; D017931:DNA Primers; D018076:DNA, Complementary; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D013431:Sulfates / Q000737:chemistry*; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism*; D014960:X Chromosome; D000097811:Carbohydrate Sulfotransferases
D000117:Acetylglucosamine; D017931:DNA Primers; D018076:DNA, Complementary; D007527:Isoenzymes; D013431:Sulfates; D015238:Sulfotransferases; D000097811:Carbohydrate Sulfotransferases