Of the five senses, taste is one of the least understood. In humans, hearing and vision are more developed than the senses of taste and smell, but the cellular machinery that relays gustatory and olfactory messages to the brain is the first line of defense for what we ingest, say chemosensory researchers. The sensation of taste also includes physical factors like temperature and texture. In fact, until recently researchers thought that fat had no taste and was detected only by its texture. Because the neurophysiological and psychological data are accruing so quickly and because of the multimillion-dollar food and beverage industry's continuing interest in taste research, investigators say that this is a very stimulating time in which to work.
Industry is particularly interested in masking bitter taste and enhancing salty taste.
This G protein causes the buildup of a second-messenger molecule called IP3. Such accumulation eventually leads to shifts in cellular ion concentrations that cause the release of a neurotransmitter. Robert Margolskee and colleagues identified gustducin, a molecule that might be important in bitter taste signal transduction. The other possible pathway involves a G protein called gustducin. Activation of gustducin causes a decrease in cyclic AMP, another type of second messenger, rather than an increase of IP3.