Redistribution of phospholipid/Ca2+-dependent protein kinase in mast cells activated by various agonists

Three types of agonists; receptor-mediated concanavalin A), direct (phorbol ester), and membrane-perturbing (compound 48/80), elicit histamine secretion from rat peritoneal mast cells. We tested whether activation of the mast cells by these agents is accompanied by subcellular redistribution of protein kinase C. Phorbol ester treatment predictably caused a profound decrease of phospholipid/Ca2+-dependent histone kinase activity in the cytosol and a concomitant increase of [3H]PMA-binding capacity in the membrane fraction, in a time- and concentration-dependent manner. Similar, but less marked effects were observed with stimulations by concanavalin A and compound 48/80. When mast cells labeled with [32P] and then stimulated with the agents, phosphorylation of a 50,000-Dalton protein was enhanced in the membrane fraction. These results suggest that protein kinase C may play a role in mast cell activation through phosphorylation of the membrane protein.