Inositol hexakisphosphate and diphosphoinositol-pentakisphosphate kinase 2 (PPIP5K2)

Bifunctional inositol kinase that acts in concert with the IP6K kinases IP6K1, IP6K2 and IP6K3 to synthesize the diphosphate group-containing inositol pyrophosphates diphosphoinositol pentakisphosphate, PP-InsP5, and bis- diphosphoinositol tetrakisphosphate, (PP)2-InsP4. PP-InsP5 and (PP)2-InsP4, also respectively called InsP7 and InsP8, regulate many different cellular processes, including apoptosis, vesicle trafficking, cytoskeletal dynamics, exocytosis, insulin signaling and neutrophil activation.

Phosphorylates inositol hexakisphosphate (InsP6) at positions 1 or 3 to generate PP-InsP5 that's subsequently phosphorylated by IP6Ks to create (PP)2-InsP4. Instead, phosphorylates at position 1 or 3 PP-InsP5, made by IP6Ks from InsP6, to create (PP)2-InsP4.