Signalling mechanisms in mouse bitter responsive taste cells.

To clarify the components involved in mouse intracellular bitter transduction in the mouse, we investigated the expression patterns of transduction components and the contribution of intracellular Ca2+ stores. Of 64 cells responding to bitter compounds, 63% of the cells expressed the taste tissue-specific G-protein alpha-gustducin. Of the alpha-gustducin immunoreactive cells, 78% expressed IP3R3, a receptor that mediates Ca2+ release from the intracellular store. When intracellular Ca2+ was depleted by treatment with the inhibitor thapsigargin, 83% of the taste cells lost their response to bitter. These data suggest that bitterness transduction involves the release of Ca2+ from intracellular stores.