title: A specific metabolic activity on the surface membrane in malignant cell-transformation.
abstract: The carbohydrate-binding protein, Concanavalin A (Con A), binds to glucose- or mannose-like sites on the cell-surface membrane. Unless the cells are treated with trypsin, this protein agglutinates malignantly transformed cells, but not normal cells. The transformed cells were agglutinated at 24 degrees C but not at 4 degrees C. Transformed and normal cells treated with trypsin were agglutinated at both 24 degrees C and 4 degrees C with high concentrations of Con A (500 mug/ml), but only at 24 degrees C with low concentrations (5 mug/ml). The same number of Con A molecules were bound to normal and transformed cells at both temperatures. The results indicate that the site for Con A on the surface membrane contains two activities, a component that binds Con A molecules (B) and a component that determines agglutination (A). B is not temperature sensitive and is active in normal and transformed cells, whereas A, which is temperature sensitive, is in an active form only in transformed cells. A can be activated by trypsin, and the increased activity per cell allows agglutination at 4 degrees C with a high, but not with a low, concentration of Con A. Agglutination of transformed cells by wheat-germ agglutinin, which binds to N-acetyl-D-glucosamine-like sites, and by soybean agglutinin, which binds to N-acetyl-D-galactosamine-like sites, was not temperature sensitive. Thus, the temperature-sensitive component A is specific for Con A, and malignant transformation of normal cells, which results in agglutinability by Con A, is associated with the activation of a specific temperature-sensitive activity on the surface membrane.
mesh_terms: D000372:Agglutination Tests; D000818:Animals; D001358:Avian Sarcoma Viruses; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D003208:Concanavalin A / Q000378:metabolism; D006224:Cricetinae; D000882:Haplorhini; D006601:Hexoses / Q000378:metabolism; D037102:Lectins / Q000378:metabolism*; D008223:Lymphoma; D008979:Moloney murine leukemia virus; D009374:Neoplasms, Experimental; D009602:Nitrosamines / Q000494:pharmacology; D011120:Polyomavirus; D011485:Protein Binding; D013696:Temperature
chemical_list: D006601:Hexoses; D037102:Lectins; D009602:Nitrosamines; D003208:Concanavalin A