Fig. 1. Domain structure of the cytosolic activators of human NADPH oxidase and its intermolecular and intramolecular interactions. Schematic drawing of the domains and motifs contained in the p47^phox, p67^phox and p40^phox proteins. The p67^phox SH3(C) constitutively interacts with the C-terminal tail region of p47^phox (red arrow). The other interactions in the resting state (blue arrows) are described (Shiose and Sumimoto, 2000; Hiroaki et al., 2001; Ito et al., 2001). PX, phox homology domain; PB1, phox and bem homology 1; PC, phox and cdc24 motif; TPR, tetratrico peptide repeat. The amino acid sequence of the p47^phox tail region, which contains a class II SH3-binding consensus, PxxPxR, is shown.