Further evidence for the involvement of the phosphorylation of 46K protein(s) in the regulation of superoxide anion production in guinea pig polymorphonuclear leukocytes

Treatment of guinea pig polymorphonuclear leukocytes (PMNL) with arachidonate at concentrations of less than 20 μ m induced slight stimulation of Superoxide anion (O − 2 ) production with little enhancement of the phosphorylation of the 46K protein(s). The stimulation of the phosphorylation of those protein(s) has been observed in parallel with an activation of NADPH oxidase in our previous studies (N. Okamura et al. (1984) Arch. Biochem. Biophys. 228 , 270–277; T. Ohtsuka et al. (1986) Biochim. Biophys. Acta 888 , 332–337; T. Ohtsuka et al. (1987) J. Biochem . 101 , 897–903). On the other hand, the phosphorylation of the same protein(s) was increased by the treatment of PMNL with 10 μ m 1-oleoyl-2-acetylglycerol (OAG), a permeable diacylglycerol, with little change in O − 2 production. Treatment of PMNL with a combination of such low concentrations of arachidonate and OAG, induced marked increase in O − 2 production in accordance with the increase in the phosphorylation of 46K protein(s) which was probably due to OAG action. Thus, it is likely that this protein phosphorylation is a prerequisite or regulatory to the stimulation of the O − 2 production by arachidonate in PMNL.