The effects of Con A on cell surface shedding in cell cultures

A cell surface immobilizing concentration of Con A inhibits the shedding of [³H]fucose-containing glycoproteins from the surface of chick embryonic leg and breast muscle cell cultures and cultures of the rat skeletal muscle cell line L6. The Con A-induced inhibition of shedding is much less in the mouse fibroblast cell line 3T3. In all 4 cell types the lectin inhibits the shedding of some fucosyl-glycoproteins more than others, especially those of a lipid-containing fraction which is excluded in Biogel A-5m chromatography. This differential nature of the Con A effect is not changed by the cytoskeletal disruptors cytochalasin B or colchicine. Con A causes an increase in the amount of trypsin-sensitive surface fucosylglycoprotein in the cell surface and appears to decrease the overall amount of cell surface degradatioon suggesting that the inhibition of shedding caused by Con A is not due to an increase in internalization and degradation. The data suggest that some shedding may occur at specific cell surface sites to which surface materials must laterally migrate.