1-phosphatidyl-1D-myo-inositol 3-phosphate (PI3P) is generated largely by the Class III PI3 kinase Phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3, Vps34), which is found in intracellular membrane complexes with Phosphoinositide 3-kinase regulatory subunit 4 (PIK3R4, Vps150), necessary for catalytic activity, localization and stability (Florey & Overholtzer 2012, Raiborg et al. 2013). These core subunits are frequently associated with other partners such as Rab5, Beclin-1 and UVRAG.

PI3P strongly upregulates phagosomal NADPH oxidase activity (Hawkins et al. 2010). This effect is mediated by PI3P binding to the PX domain of Neutrophil cytosol factor 4 (NCF4, p40phox), a component of the NOX2 complex. PI3P controls ROS production by regulating the presence of NCF4 and NCF2 (p67phox) at the phagosomal membrane (Song ZM et al. 2017).