Concanavalin A-Induced Decrease in Cell Surface Charge and its Modification by Sulfhydryl Blocking Agents

Abstract

The electric surface charge of mouse melanoma B 16-C 2 W cells treated with various concentrations of Con A was determined by cell electrophoresis. At Con A concentrations higher than 5 μg/ml, the cellular electrophoretic mobility decreased significantly at 10 minutes incubation, but this effect was reversed by α-methyl-D-mannoside. At these higher Con A concentrations, more than 30% of Con A receptors were bound with lecitn. Pretreatment of cells with sulfhydryl blocking agents, 10-5 M p-chloromercuribenzoic acid or 10-5M N-ethylmaleimide, completely prevented the subsequent Con A-induced mobility reduction without changing the amount of Con A-binding to the cell surface. Similar effects were found with pretreatment with protein linkage agents, such as 2% glutaraldehyde and 10-6M fluorescein mercuric acetate. The removal of chondroitin sulfate with the specific enzyme resulted in a 30% decrease in electrophoretic mobility of intact cells but produced no change in Con A-treated cells. These results suggest that Con A treatment may induce an alteration in chondroitin sulfate distributions at the cell surface and that sulfhydryl residues of membrane proteins may play an important role in this surface alteration.