The immediate activator of the NADPH oxidase is arachidonate not phosphorylation.
Superoxide generation is rapidly triggered following the addition of a stimulus to neutrophils. The signal-transduction pathway culminates in the activation of protein kinase C, whose phosphorylation of a protein component is considered to activate the oxidase. Arachidonate stimulated the oxidase in a concentration-dependent manner but, unlike phorbol-12-myristate-13-acetate (PMA), was not inhibited by staurosporine, a protein kinase inhibitor. Increase protein phosphorylation, apparent with PMA, was not observed when superoxide generation was triggered by arachidonate. Inhibitors of phospholipase A2 inhibit the PMA activation of the oxidase. Therefore, we propose that arachidonate and not phosphorylation is the immediate stimulus for superoxide generation.
Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, England.
L M
LM
Henderson
S K
SK
Moule
J B
JB
Chappell
D000470:Alkaloids / Q000494:pharmacology; D000605:Amino Alcohols / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology; D009861:Onium Compounds / Q000494:pharmacology; D010750:Phosphoproteins / Q000502:physiology; D010766:Phosphorylation; D019311:Staurosporine; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D000605:Amino Alcohols; D009861:Onium Compounds; D010750:Phosphoproteins; D013481:Superoxides; C062204:Ro 31-4639; D016718:Arachidonic Acid; C007517:diphenyleneiodonium; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate