Description
This enzyme also phosphorylates Ins(1,4,5)P3 to Ins(1,3,4,5)P4, Ins(1,3,4,5)P4 to Ins(1,3,4,5,6)P5, and Ins(1,3,4,5,6)P4 to Ins(PP)P4, isomer unknown. The enzyme from the plant Arabidopsis thaliana can also phosphorylate Ins(1,3,4,6)P4 and Ins(1,2,3,4,6)P5 at the D-5-position to produce 1,3,4,5,6-pentakisphosphate and inositol hexakisphosphate (InsP6), respectively. Yeast produce InsP6 from Ins(1,4,5)P3 by the actions of this enzyme and EC 2.7.1.158, inositol-pentakisphosphate 2-kinase.
Reaction
2 ATP + 1D-myo-inositol 1,4,5-trisphosphate = 2 ADP + 1D-myo-inositol 1,3,4,5,6-pentakisphosphate (overall reaction); (1a) ATP + 1D-myo-inositol 1,4,5-trisphosphate = ADP + 1D-myo-inositol 1,4,5,6-tetrakisphosphate; (1b) ATP + 1D-myo-inositol 1,4,5,6-tetrakisphosphate = ADP + 1D-myo-inositol 1,3,4,5,6-pentakisphosphate
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