Inositol phosphate kinase with a broad substrate specificity. Phosphorylates inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), inositol 1,4,5,6-tetrakisphosphate (Ins(1,4,5,6)P4), inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), inositol 1,3,4,6-tetrakisphosphate (Ins(1,3,4,6)P4) and inositol 1,2,3,4,6-pentakisphosphate (Ins(1,2,3,4,6)P5) but not inositol 1,4-bisphosphate (Ins(1,4)P2), inositol 1,3,4-trisphosphate (Ins(1,3,4)P3), inositol 1,2,6-trisphosphate (Ins(1,2,6)P3), inositol 3,4,5,6-tetrakisphosphate (Ins(3,4,5,6)P4), inositol 1,3,4,5,6-pentakisphosphate (Ins(1,3,4,5,6)P5), inositol 1,2,4,5,6-pentakisphosphate (Ins(1,2,4,5,6)P5) or inositol hexakisphosphate (InsP6). Involved in the auxin signaling pathway. Regulates axillary shoot branching and is required for phytate synthesis in seeds. 1D-myo-inositol 1,4,5-trisphosphate + 2 ATP = 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + 2 ADP + 2 H(+) 1D-myo-inositol 1,3,4,6-tetrakisphosphate + ATP = 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + ADP + H(+) Down-regulated by KIN10 through its protein phosphorylation. Interacts with KIN10 and KIN11. Expressed in leaves, stems, roots, siliques and flowers. Detected in vascular strands, stigma cells, the abscission zones of fully elongated siliques, the root central cylinder and the root tip. Expressed in mature pollen, but not in immature pollen grains. Induced by auxin, but not by salt, abscisic acid, mannitol, water or drought. Phosphorylated by KIN10. Loss-of-function mutant atIpk2beta-1 (T-DNA insertion) is fully complemented by AtIPK2alpha in tissue but not in seeds, leading to the generation of phytate-free seeds. Increased sensitivity to 6% glucose during seedling development and decreased germination in response to the gibberellin biosynthesis inhibitor paclobutrazol (PAC) (PubMed:29216370). Does not bind calmodulin. Belongs to the inositol phosphokinase (IPK) family.