Significance of Phosphorylation/Dephosphorylation of 46K Protein(s)in Regulation of Superoxide Anion Production in Intact Guinea Pig Polymorphonuclear Leukocytes1

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Abstract
Superoxide anion (O 2− ) production stimulated by concanavalin A (Con A) in guinea pig polymorphonuclear leukocytes (PMNL) was suppressed by addition of methyl-α-mannoside, a Con A inhibitor, and resumed upon readdition of Con A. The reversible change in the O 2− production was assumed to reflect the change in NADPH oxidase activity measured for the 30,000 × g particulate fraction. The stimulation by Con A of the phosphorylation of 46K protein(s), as observed previously with several membrane-perturbing agents in parallel with an activation of NADPH oxidase in intact guinea pig PMNL (Okamura, N., et al. (1984) Arch. Biochem. Biophys. 228, 270–277), was also suppressed by methyl-α-mannoside and resumed upon readdition of Con A. Similar parallelism between the phosphorylation and NADPH oxidase activity was also observed in the case of stimulation by N -formyl-methionyl-leucyl-phenylalanine (FMLP) and phorbol 12-myristate 13-acetate (PMA), though both processes were reversible after the stimulation by FMLP but not reversible after that by PMA. Thus, such a parallelism observed in both intact PMNL and 30,000 × g particulate fraction indicates possible involvement of the protein phosphorylation in the regulation of the production of active oxygen metabolites in PMNL.