title: Age-related changes induced by tunicamycin in wheat germ agglutinin binding to chick embryo fibroblasts.
abstract: The specific roles of N-acetylglucosaminyl and sialyl residues were investigated in the binding of wheat germ agglutinin (WGA) to fibroblasts from 8- and 16-day chick embryos. Cells from the 8-day embryos exhibited two classes of WGA binding site, whereas fibroblasts from 16-day embryos only displayed one. Neuraminidase treatment of fibroblasts from 8-day embryos raised the number of WGA binding sites with a high affinity constant and reduced the number of sites with a low affinity constant. In 16-day cells, neuraminidase treatment reduced the number of WGA binding sites. The data presented here suggest that WGA binds to cell-surface glycoproteins containing sialic acid residues. This tendency was more marked in 16-day than in 8-day cells and corresponded to the finding that neuraminidase released more sialic acid from the surface of 16-day cells than of 8-day cells. Glycosylation of cell-surface N-linked glycoproteins did not seem essential in determining the WGA binding capacity, as shown by the effect of tunicamycin on fibroblasts from both 8- and 16-day embryos. In the absence of N-glycosylated binding sites, WGA bound to O-glycosylated structures and the older tunicamycin-treated embryo cells exhibited a larger number of WGA binding sites than the younger tunicamycin-treated cells, in relation to the increase of the amount of O-glycosylated structures during embryo development.
mesh_terms: D000375:Aging; D000818:Animals; D001665:Binding Sites; D002642:Chick Embryo; D005347:Fibroblasts / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives*; D006023:Glycoproteins / Q000378:metabolism*; D037102:Lectins / Q000494:pharmacology*; D009439:Neuraminidase / Q000494:pharmacology; D012794:Sialic Acids / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology*; D014909:Wheat Germ Agglutinins
chemical_list: D006023:Glycoproteins; D037102:Lectins; D012794:Sialic Acids; D014909:Wheat Germ Agglutinins; D014415:Tunicamycin; D009439:Neuraminidase; D005944:Glucosamine