The recent application of molecular biological techniques to taste cells has led to the identification and cloning of a number of proteins that are involved in signal transduction. Some of these are expressed only in taste cells, whereas others are expressed at higher levels in taste cells than in other, non-sensory lingual cells. Among these proteins are several G protein alpha subunits, of which alpha gustducin is particularly interesting because of its similarity to the alpha transducins expressed in the visual system, suggesting that there are similarities in taste and visual transduction mechanisms.