d-myo-inositol-1,4,5-triphosphate

D-myo-Inositol-1,4,5-triphosphate tripotassium (Ins(1,4,5)-P3 tripotassium) is a second messenger in cellular signal transduction that triggers Ca2+ mobilization.

D-myo-Inositol-1,4,5-triphosphate trisodium (Inositol 1,4,5-trisphosphate trisodium) is a second messenger produced in cells by the phospholipase C-mediated hydrolysis of phosphatidylinositol-4,5-bisphosphate. It binds to Ins(1,4,5)P3 receptors, resulting in the opening of calcium channels and an increase in intracellular calcium.

Ins(1,4,5)P3 is an isomer of the biologically important D-myo-inositol-1,4,5-triphosphate. Unlike its isomer, Ins(1,4,5)P3 does not evoke a rise in intracellular calcium when added to cells. It is not known if Ins(1,4,5)P3 can act as a competitive inhibitor of biologically-active inositol phosphates.

D-myo-Inositol-1,3,4,5-tetraphosphate (Ins(1,3,4,5)-P4) is formed by the phosphorylation of Ins(1,4,5)P3 by inositol 1,4,5-triphosphate 3-kinase. Ins(1,3,4,5)-P4 increases intracellular calcium levels by two distinct mechanisms: opening calcium channels on both the endoplasmic reticulum to release calcium from internal stores and on the plasma membrane to allow the influx of calcium from outside the cell.