D-myo-Inositol-3,4,5-triphosphate (Ins(3,4,5)-P3) is a structural analog of Ins(1,4,5)-P3 and a member of the inositol phosphate (InsP) cell signaling family of molecules. D-myo Ins(3,4,5)-P3 is 200-fold less potent than D-myo Ins(1,4,5)-P3 at initiating Ca++ release when injected into Xenopus oocytes. Ins(1,4,5)-P3 binds to Type 1, 2, and 3 subtypes of the rat recombinant IP3 receptor with Ki values of less than 25 nM, whereas Ins(3,4,5)-P3 exhibits significantly lower affinity with Ki values of 3-11 µM.