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).
Schink, KO, Raiborg, C, Stenmark, H
1-phosphatidylinositol-3-kinase activity of PIK3C3:PIK3R4 [phagocytic vesicle membrane]
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