Background：

Inositol phosphate kinase with a broad substrate specificity. Phosphorylates inositol 1，4，5-trisphosphate (Ins(1，4，5)P3) first to inositol 1，3，4，5-tetrakisphosphate and then to inositol 1，3，4，5，6-pentakisphosphate (Ins(1，3，4，5，6)P5). Phosphorylates inositol 1，3，4，6-tetrakisphosphate (Ins(1，3，4，6)P4). Phosphorylates glycero-3-phospho-1D-myo-inositol 4，5-bisphosphate to glycero-3-phospho-1D-myo-inositol 3，4，5-trisphosphate. Plays an important role in MLKL-mediated necroptosis via its role in the biosynthesis of inositol pentakisphosphate (InsP5) and inositol hexakisphosphate (InsP6). Binding of these highly phosphorylated inositol phosphates to MLKL mediates the release of an N-terminal auto-inhibitory region， leading to activation of the kinase. Essential for activated phospho-MLKL to oligomerize and localize to the cell membrane during necroptosis. Required for normal embryonic development， probably via its role in the biosynthesis of inositol 1，3，4，5