SH3 domain-mediated interactions involving the phox components of the NADPH oxidase

Abstract.

Objective and Design: To derive a model describing the SH3 domain-mediated assembly of the activated NADPH oxidase.¶Materials: Recombinant SH3 domain and Pro-rich fusion proteins were used to investigate potential co-associations.¶Methods: Interactions were assessed using biotinylated overlay assays and the yeast two hybrid system. Association with p47^phox from cell lysates was examined by immunoblot analysis.¶Results: The association between p47- and p22^phox involves the SH3 domains of p47^phox functioning in tandem. The Pro-rich motif in p47^phox interacts with both p40^phox and the COOH-terminal SH3 domain of p67^phox.¶Conclusions: In the resting cell, the Pro-rich motif of p47^phox interacts with the SH3 domain of p40^phox, which in turn associates with p67^phox. Upon activation, the p47-p40^phox regulatory complex dissociates, permitting the association of p47^phox with the COOH-terminal SH3 domain of p67^phox. This complex translocates to the plasma membrane and associates with cytochrome b₅₅₈, via interaction of the tandem SH3 domains of p47^phox with the p22^phox Pro-rich motif.