The NADPH-oxidase-associated H+ channel is opened by arachidonate.
The H+ channel associated with the generation of O2.- by NADPH oxidase and the oxidase itself must both be activated in response to stimuli (e.g. phorbol esters, chemotactic peptides, certain fatty acids). We have investigated the effects of membrane potential, an imposed pH gradient and a combination of the two (the protonmotive force) on the H+ conductivity of the cytoplast membrane. H+ conductivity was observed only in the presence of arachidonate and not in its absence. In the presence of arachidonate, H+ movement was determined by the protonmotive force. The effect of arachidonate was probably on a channel, since this fatty acid did not significantly increase the H+ permeability of artificial phospholipid membranes. It appears, therefore, that arachidonate is required both for the activation of O2.- production and the associated H(+)-channel-mediated efflux.
Henderson
L M
LM
Department of Biochemistry, School of Medical Sciences, University of Bristol, U.K.
Chappell
J B
JB
D016718:Arachidonic Acid / Q000494:pharmacology*; D002352:Carrier Proteins / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D008081:Liposomes / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D009247:NADH, NADPH Oxidoreductases / Q000502:physiology*; D019255:NADPH Oxidases; D027961:Potassium-Hydrogen Antiporters; D013481:Superoxides / Q000378:metabolism
D002352:Carrier Proteins; D007473:Ion Channels; D008081:Liposomes; D027961:Potassium-Hydrogen Antiporters; D013481:Superoxides; D016718:Arachidonic Acid; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases