Changes in protein phosphorylation in guinea pig polymorphonuclear leukocytes by treatment with membrane-perturbing agents which stimulate superoxide anion production

Abstract

Phosphorylation of proteins was examined in guinea pig polymorphonuclear leukocytes in relation to the effects of membrane-perturbing agents, which stimulate superoxide anion production, and their inhibitors. The phosphorylation was detected by 32P autoradiography after separation by two-dimensional electrophoresis of proteins phosphorylated in 32P-preloaded cells. Though phosphorylation of various proteins was stimulated by each of the membrane-perturbing agents, the stimulation was especially marked in six proteins. Phorbol myristate acetate and digitonin enhanced the phosphorylation of the six proteins, while myristate and concanavalin A increased the phosphorylation of five and three proteins, respectively, out of the six proteins, p-Bromophenacyl bromide, an inhibitor of phospholipase A 2, inhibited the stimulatory effect of phorbol myristate acetate on both superoxide anion production and protein phosphorylation. Trifluoperazine, a calmodulin inhibitor, also inhibited the effect of phorbol myristate acetate on both, except for an increase in the phosphorylation of one out of the six proteins. α-Methylmannoside, an inhibitor of concanavalin A binding, inhibited the stimulation of the phosphorylation of the three proteins by concanavalin A. The results indicate that the activation of superoxide anion production by the membrane-perturbing agents in guinea pig polymorphonuclear leukocytes is accompanied by the phosphorylation of, at least some of, these six proteins.