Converts inositol hexakisphosphate (InsP6) to diphosphoinositol pentakisphosphate (InsP7/PP-InsP5). Converts 1,3,4,5,6-pentakisphosphate (InsP5) to PP-InsP4 (By similarity). 1D-myo-inositol hexakisphosphate + ATP = 5-diphospho-1D-myo-inositol 1,2,3,4,6-pentakisphosphate + ADP 1-diphospho-myo-inositol 2,3,4,5,6-pentakisphosphate + ATP + H(+) = 1,5-bis(diphospho)-1D-myo-inositol 2,3,4,6-tetrakisphosphate + ADP Belongs to the inositol phosphokinase (IPK) family.