Expression of α-gustducin in mammalian retinas.

α-Gustducin (Gα-gust) is the α subunit of the heterotrimeric G-protein complex specific for taste receptor cells of the tongue. However, it has been shown to be present in ectopic regions, such as airways and digestive tract. Recently, Gα-gust was found within neurons in various regions of the mouse brain. In this study, we tested whether Gα-gust is expressed in the mammalian retina. Gα-gust was identified in mouse, rat, and rabbit retinas by western blot and immunohistochemistry analyses. Double-labeling experiments in the mouse retina clearly showed that Gα-gust is exclusively expressed in the axon terminals of the rod bipolar cells. The evidence suggests that Gα-gust may selectively participate in signal transduction in the axon terminals of rod bipolar cells in the mammalian retina.