We cloned cDNAs for two G protein alpha-subunits belonging to the Galphaq family, each capable of activating PLCbeta, from rat tongue. One is a Galphaq in the narrow sense, and the other, termed rat Galpha15, is a rat counterpart of mouse Galpha15, sharing an amino acid sequence similarity of 94%. RT-PCR and Northern blot analysis demonstrated that rat Galpha15 and Galphaq were distinctly expressed in tongue epithelia containing taste buds. Immunostaining also showed that rat Galpha15, together with the Galphaq, was localized mainly in taste buds. These studies suggest the possibility that these two Galpha proteins function for taste signal transduction in sensory cells.