At the plasma membrane, phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) 3-kinase catalytic subunits form complexes with regulatory subunits. These complexes along with phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing subunits alpha (PIK3C2A), beta (PIK3C2B), and gamma (PIK3C2G) phosphorylate phosphatidylinositol 4-phosphate (PI4P) to phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). 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: PIK3C2A (Arcaro et al. 2000); PIK3C2B (Arcaro et al. 2000, Arcaro et al. 1998); PIK3C2G (Misawa et al. 1998, Ono et al. 1998); PIK3CA:PIK3R1, PIK3CA:PIK3R2, PIK3CA:PIK3R3 (Vanhaesebroeck et al. 1997); PIK3CB:PIK3R1, PIK3CB:PIK3R2, PIK3CB:PIK3R3 (Meier et al. 2004, Guo et al. 1997); PIK3CD:PIK3R1, PIK3CD:PIK3R2, PIK3CD:PIK3R3 (Vanhaesebroeck et al. 1997); and PIK3CG:PIK3R5, PIK3CG:PIK3R6 (Suire et al. 2005, Stoyanov et al. 1995).