Taste receptor gene expression outside the gustatory system

The sense of taste facilitates the recognition of beneficial or potentially harmful food constituents prior to ingestion. For the detection of tastants, epithelial specializations in the oral cavity are equipped with taste receptor molecules that interact with sweet, umami (the taste of L-amino acids), salty, sour, and bittertasting substances. Over the past years, numerous tissues in addition to gustatory sensory tissue have been identified to express taste receptor molecules. These findings bear important implications for the roles taste receptors fulfill in vertebrates, which are currently envisioned much broader than thought previously. Taste receptive molecules are present in the brain, respiratory and gastrointestinal tracts, heart, male reproductive tissue, as well as other areas of the body just beginning to emerge. This review summarizes current knowledge on the occurrence and functional implications of taste receptive molecules outside the oral cavity.