It is commonly assumed that activation of the superoxide-generating NADPH oxidase requires the formation of a stable complex between flavocytochrome b-245 (the gp91phox/p22phox heterodimer) and the cytosolic cofactors p47phox, p67phox and Rac2. This association is thought to convert flavocytochrome b-245, which contains the NADPH-binding site, flavin and haem centres, from an inactive into an active state. Here we provide evidence that, in the cell-free system, this activation process does not necessarily require the formation of a stable stoichiometric complex between the phox proteins. To explain this data we propose the hypothesis that p67phox (and possibly Rac2), are capable of activating flavocytochrome b-245 in a catalytic fashion, where a single molecule of p67phox (or Rac2) is capable of activating multiple flavocytochrome b-245 molecules.
The mechanism of activation of NADPH oxidase in the cell-free system: the activation process is primarily catalytic and not through the formation of a stoichiometric complex
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Andrew R. CROSS, Richard W. ERICKSON, John T. CURNUTTE; The mechanism of activation of NADPH oxidase in the cell-free system: the activation process is primarily catalytic and not through the formation of a stoichiometric complex. Biochem J 15 July 1999; 341 (2): 251–255. doi: https://doi.org/10.1042/bj3410251
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