Anionic amphiphile-independent activation of the phagocyte NADPH oxidase in a cell-free system by p47(phox) and p67(phox), both in C terminally truncated forms. Implication for regulatory Src homology 3 domain-mediated interactions

Kenichiro Hata, Takashi Ito, Koichiro Takeshige, Hideki Sumimoto

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Anionic amphiphiles, such as arachidonate, activate the superoxide- producing phagocyte NADPH oxidase in a cell-free system with human neutrophil membrane, which contains cytochrome b558 comprising gp91(phox) and p22(phox), and three cytosolic proteins: p47(phox) and p67(phox), each harboring two SH3 domains, and the small GTPase Rac. Here we show that, even without the amphiphiles, the oxidase is activated in vitro by a C terminally truncated p47(phox), retaining the N-terminal and the two SH3 domains, and the N terminus of p67(phox). When either truncated p47(phox) or p67(phox) is replaced by the respective full-length one, the activation absolutely requires the amphiphiles. The results indicate that both p47(phox) and p67(phox) are the primary targets of the amphiphiles, and that their C- terminal regions play negative regulatory roles. We also find that the truncated p47(phox), but not the full-length one, can bind to p22(phox), a binding required for the oxidase activation. The N-terminal SH3 domain of p47(phox) is responsible for the binding not only to p22(phox), but also to the p47(phox) C terminus. Thus the SH3 domain is accessible in the active p47(phox), but is normally masked in the full-length one probably via intramolecularly interacting with the C terminus. The present findings support our previous proposal of regulatory SH3 domain-mediated interactions.

Original languageEnglish
Pages (from-to)4232-4236
Number of pages5
JournalJournal of Biological Chemistry
Issue number7
Publication statusPublished - Feb 13 1998


All Science Journal Classification (ASJC) codes

  • Biochemistry

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