The Ca²⁺ signaling cascade has been reported to be activated by many tastants in vertebrate taste systems. Recently we have shown that G_i2 and phospholipase Cβ2 (PLCβ2) are co-expressed in a subset of taste bud cells and are possibly involved in Ca²⁺ triggering of taste signaling in rats. We report here that, as a component downstream of PLCβ2, the type 3 isoform of the inositol 1,4,5-trisphosphate (IP₃) receptor (IP₃R3) is specifically expressed in the same cells as PLCβ2 in rat taste buds. We also show that cells expressing rT2R9, a probable cycloheximide receptor, are included among PLCβ2- and IP₃R3-positive cells, as in the case of rT1R2, a different type of taste receptor. Our findings indicate that PLCβ2 and IP₃R3 co-localize together with G_i2 as downstream components of two different types of taste receptors, T1R and T2R, in taste bud cells.