D-myo-Inositol 1,4,5-trisphosphate hexapotassium salt is the hexapotassium salt of D-myo-Inositol 1,4,5-trisphosphate (1,4,5-IP3), which is a second messenger that stimulates the discharge of calcium from the endoplasmic reticulum. In Vitro: Second messenger D-myo-Inositol 1,4,5-trisphosphate (1,4,5-IP3) is served as an inositol phosphate derivative. The dissociation constant (K_D) for Pr55^Gag complexed with D-myo-Inositol 1,4,5-trisphosphate (an inositol with divalent phosphate groups and devoid of lipid groups) is 2170 μM. The binding affinities of D-myo-Inositol 1,4,5-trisphosphate (K_D=568 μM) and 1,3,4,5-IP4 (K_D=526 μM) for matrix (MA) are almost identical^[1].