Advan. Enzyme Regul. 44 (2004) 279–298 The role of phosphoinositides and phosphorylation in regulation of NADPH oxidase Olga Perisic a, *, Michael I. Wilson a , Dimitrios Karathanassis a , Jer ! onimo Bravo b , Michael E. Pacold a , Chris D. Ellson c , Phillip T. Hawkins c , Len Stephens c , Roger L. Williams a a MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK b Structural Biology Program, Centro Nacional de Investigaciones Oncol ! ogicas, Melchor Fern ! andez Almagro 3, E-28029 Madrid, Spain c The Inositide Laboratory, The Babraham Institute, Cambridge CB2 4AT, UK Introduction In professional phagocytes, superoxide (O 2  ) production by activated NADPH oxidase is a vital step in destruction of invading microorganisms, either directly or indirectly through activation of proteases (Babior, 1999; Reeves et al., 2002; Vignais, 2002). The importance of this process is apparent from the life-threatening and recurrent infections that occur in individuals with chronic granulomatous disease (CGD), which are caused by hereditary mutations in the NADPH oxidase complex. More recently, distinct isoforms of NADPH oxidase have been characterized in a variety of tissues (Lambeth, 2002; Banfi et al., 2003; Geiszt et al., 2003; Lassegue and Clempus, 2003; Takeya et al., 2003). The potentially damaging reactive oxygen species (ROS) produced by NADPH oxidase catalysis necessitate its tight regulation in cells. The main catalytic component, flavocytochrome b 558 , is an integral membrane protein complex consisting of gp91 phox and p22 phox , while the regulatory components p40 phox , p47 phox , p67 phox and Rac reside in the cytosol of the resting cells. The p40 phox , p47 phox and p67 phox subunits have a modular organization, and it is clear that both intramolecular and intermolecular domain–domain interactions are essential for both the suppression of activity in resting cells and augmentation of activity in the stimulated cells. The phosphorylation of NADPH oxidase subunits triggers rewiring of resting-state interactions and establishment of a new network of protein–protein and protein–lipid interactions, resulting in activation of the enzyme. ARTICLE IN PRESS *Corresponding author. 0065-2571/$ - see front matter r 2003 Published by Elsevier Ltd. doi:10.1016/j.advenzreg.2003.11.003