At the plasma membrane, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunits form complexes with regulatory subunits. These complexes phosphorylate phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) to phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) (Stephens et al. 1997). The PI(4,5)P2 3-kinase complexes involved are: PI(4,5)P2 3-kinase catalytic subunit alpha isoform (PIK3CA) bound to PI 3-kinase regulatory subunit alpha/beta/gamma (PIK3R1/2/3); beta (PIK3CB) bound to PIK3R1/2/3; delta (PIK3CD) bound to PIK3R1/2/3; and gamma (PIK3CG) bound to PI 3-kinase regulatory subunit 5 (PIK3R5) or 6 (PIK3R6).
The following lists the above proteins with their corresponding literature references: PIK3CA:PIK3R1, PIK3CA:PIK3R2, PIK3CA:PIK3R3 (Dey et al. 1998, Vanhaesebroeck et al. 1997, Meier et al. 2004); PIK3CB:PIK3R1, PIK3CB:PIK3R2, PIK3CB:PIK3R3 (Meier et al. 2004); PIK3CD:PIK3R1, PIK3CD:PIK3R2, PIK3CD:PIK3R3 (Vanhaesebroeck et al. 1997, Meier et al. 2004); and PIK3CG:PIK3R5, PIK3CG:PIK3R6 (Voigt et al. 2006, Suire et al. 2005, Stoyanov et al. 1995).