Phosphorylates Ins(1,3,4,5,6)P5 at position 2 to form Ins(1,2,3,4,5,6)P6 (InsP6 or phytate). Phytate is a regulator of intracellular signaling, a highly abundant animal antinutrient, and a phosphate store in plant seeds. Also phosphorylates Ins(1,3,4,6)P4 and Ins(1,4,5,6)P4 to produce Ins(1,2,3,4,6)P5 and Ins(1,2,4,5,6)P5. 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + ATP = 1D-myo-inositol hexakisphosphate + ADP + H(+) Binds 1 zinc ion per subunit. Strongly expressed in leaves and cauline leaves. Weakly expressed in siliques and flowers. In flower, it is expressed in the major organs of developing flower buds. Strongly expressed in sepals, petals, in the male and female organs of immature and mature flower buds. Strongly expressed in the gynoecium and carpels which are fused to form the gynoecium. Also expressed in the transmitting tissue and ovules. The EXKPK motif is conserved in inositol-pentakisphosphate 2-kinases of both family 1 and 2. The gene coding for this protein might be inactivated to commercially produce plants with phytate-free grain. Indeed, while the role of phytate (InsP6) accumulation in seeds is unknown, it causes nutritional and environmental problems, partly due to the inability of monogastric animals to digest it. Belongs to the IPK1 type 2 family.