Sulfation of endothelial mucin by corneal keratan N-acetylglucosamine 6-O-sulfotransferase (GST-4beta).
Intestinal N-acetylglucosamine 6-O-sulfotransferase (I-GlcNAc6ST, GST-4alpha) and corneal N-acetylglucosamine 6-O-sulfotransferases (C-GlcNAc6ST, GST-4beta) are two highly homologous GlcNAc 6-O-sulfotransferase isozymes encoded by two intronless open reading frames that reside approximately 50 kb apart on human chromosome 16q23.1. I-GlcNAc6ST has been shown to catalyze 6-O-sulfation of the endothelial mucin GlyCAM-1. C-GlcNAc6ST catalyzes 6-O-sulfation of GlcNAc in keratan sulfate and null-mutations in its encoding gene cause human macular corneal dystrophy. We show here that C-GlcNAc6ST efficiently catalyzes sulfation of GlyCAM-1 when coexpressed with the latter in COS-7 cells. We have further compared expression in human of both enzymes by Northern analysis with isozyme-specific probes. While I-GlcNAc6T is expressed mostly in intestinal tissue, larger C-GlcNAc6ST transcripts are found predominantly in the brain.
Bartes
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Department of Respiratory Diseases, Roche Bioscience, 3401 Hillview Avenue, Palo Alto, California 94304, USA.
Bhakta
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Hemmerich
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D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D003315:Cornea / Q000201:enzymology*; D004727:Endothelium / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009077:Mucins / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D015238:Sulfotransferases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution; D014162:Transfection; D000097811:Carbohydrate Sulfotransferases
D009077:Mucins; D012333:RNA, Messenger; D015238:Sulfotransferases; D000097811:Carbohydrate Sulfotransferases; C075185:sulfated glycoprotein p50