title: A murine cytotoxic T lymphocyte cell line resistant to Vicia villosa lectin is deficient in UDP-GalNAc:beta-galactose beta 1,4-N-acetylgalactosaminyltransferase.
abstract: We have reported the presence of N-acetylgalactosamine linked beta 1,4 to galactose on O-linked oligosaccharides of a cloned murine cytotoxic T cell line and the absence of these residues from the O-linked structures of a Vicia villosa lectin-resistant mutant line, VV6, derived from parental B6.1.SF.1 cells (Conzelmann, A., and Kornfeld, S. (1984) J. Biol. Chem. 259, 12528-12535). This study shows that B6.1.SF.1 cells contain an enzyme which transfers N-acetylgalactosamine from UDP-GalNAc onto the O-linked tetrasaccharides of human glycophorin A, giving rise to pentasaccharides which contain beta-glycosidically linked N-acetylgalactosamine. Desialylated glycophorin was inactive as an acceptor. The enzyme also transfers N-acetylgalactosamine to the N-linked oligosaccharides of the Tamm-Horsfall glycoprotein. This glycoprotein is known to contain N-linked oligosaccharides with beta-linked N-acetylgalactosamine residues which constitute the Sda blood group determinant. This N-acetylgalactosaminyltransferase could not be detected in VV6 cells which can account for the lack of beta-linked N-acetylgalactosamine residues on its O-linked oligosaccharides. The two cell lines have comparable levels of UDP-GalNAc:apomucin N-acetylgalactosaminyltransferase, demonstrating that the enzyme deficiency in VV6 cells is selective. Both cell lines have a similar glycolipid content, with the major component being asialo-GM1. Since this glycolipid contains N-acetylgalactosamine linked beta 1,4 to galactose, it would appear that the N-acetylgalactosyltransferase involved in the biosynthesis of glycolipids is different from the UDP-GalNAc:glycoprotein N-acetylgalactosaminyltransferase. An independently derived murine CTL line also contains the UDP-GalNAc:glycoprotein N-acetylgalactosaminyltransferase, suggesting that the expression of this enzyme is a common characteristic of this type of cell line.
mesh_terms: D000818:Animals; D002460:Cell Line; D004351:Drug Resistance; D005700:Galactosyltransferases / Q000172:deficiency* / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D037102:Lectins / Q000494:pharmacology*; D051379:Mice; D017350:N-Acetylgalactosaminyltransferases; D037121:Plant Lectins; D013379:Substrate Specificity; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology* / Q000276:immunology; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D005700:Galactosyltransferases; D037102:Lectins; D017350:N-Acetylgalactosaminyltransferases; D037121:Plant Lectins; D000097763:Polypeptide N-acetylgalactosaminyltransferase; C042242:Vicia lectins