title: Endogenous cell surface lectin in Dictyostelium: quantitation, elution by sugar, and elicitation by divalent immunoglobulin.
abstract: The amount of total endogenous cellular and cell surface lectin in aggregating Dictyostelium purpureum was determined by a number of immunochemical techniques. The results show that of the 5 x 10(6) molecules of the lectin (called purpurin) per aggregating cell only about 2% (1 x 10(5) molecules) is present on the cell surface. Cell surface purpurin can be specially eluted by lactose, which indicates that it is held to the surface by its carbohydrate-binding site. The eluted purpurin is replaced on the cell surface within 45 min. Estimates of cell surface purpurin made by binding of specific immunoglobulin to the cells at 4 degrees C indicate that a much larger amount, about 1 x 10(6) molecules, becomes associated with the cell surface in the presence of this divalent ligand. In contrast, univalent antibody fragments do not have this effect.
mesh_terms: D000908:Antibodies, Fungal; D000937:Antigen-Antibody Reactions; D002462:Cell Membrane / Q000032:analysis; D004023:Dictyostelium / Q000032:analysis* / Q000648:ultrastructure; D007074:Immunoglobulin G; D007785:Lactose / Q000494:pharmacology; D037102:Lectins / Q000032:analysis* / Q000276:immunology
chemical_list: D000908:Antibodies, Fungal; D007074:Immunoglobulin G; D037102:Lectins; D007785:Lactose