title: Enzymatic basis for a lectin-resistant phenotype: increase in a fucosyltransferase in mouse melanoma cells.
abstract: In the search for the biochemical basis of the control of glycosylation of cell surface carbohydrates, revertant clones were isolated from previously characterized wheat germ agglutinin-resistant clones of B16 mouse melanoma cells by selection for resistance to Lotus tetragonolobus lectin or to ricin. Comparison of the wheat germ agglutinin-resistant clones with the parent and revertant clones indicated that this phenotype was correlated with an increased sensitivity to the Lotus lectin, a 60- to 70-fold increase in alpha 1 leads to 3 fucosyltransferase activity and a decreased sialic acid content of the N-glycosidic chains of glycoproteins. The results suggest a novel type of control mechanism for lectin resistance, an increase in a glycosyltransferase activity. The presence of alpha 1 leads to 3 bound fucose on N-acetylglucosamine residues would interfere with the addition of sialic acid by alpha 2 leads to 3 linkages to galactose residues in the carbohydrate units, and this change could explain the resistance to wheat germ agglutinin and the increased sensitivity to the Lotus lectin. A change in a regulatory gene for the fucosyltransferase as a possible primary cause for the changed phenotype is discussed.
mesh_terms: D000818:Animals; D004351:Drug Resistance; D005647:Fucosyltransferases / Q000378:metabolism*; D006020:Glycopeptides / Q000032:analysis; D006602:Hexosyltransferases / Q000378:metabolism*; D037102:Lectins / Q000494:pharmacology*; D008545:Melanoma / Q000201:enzymology*; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D008970:Molecular Weight; D009374:Neoplasms, Experimental; D011975:Receptors, Mitogen / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014909:Wheat Germ Agglutinins
chemical_list: D006020:Glycopeptides; D037102:Lectins; D008565:Membrane Proteins; D011975:Receptors, Mitogen; D014909:Wheat Germ Agglutinins; D005647:Fucosyltransferases; D006602:Hexosyltransferases