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.