Pure and Applied Chemistry

Abstract: Taste transduction is a specialized form of signal transduction by which taste receptor cells (TRCs) encode at the cellular level information about chemical substances encountered in the oral environment (so-called tastants). Bitter and sweet taste transduction pathways convert chemical information into a cellular second messenger code utilizing cyclic nucleotides, inositol trisphosphate, and/or diacyl glycerol. These messengers are components of signaling cascades that lead to TRC depolarization and Ca++ release. Bitter and sweet taste transduction pathways typically utilize taste-specific or taste-selective seven transmembrane-helix receptors, G proteins, effector enzymes, second messengers, and ion channels. The structural and chemical diversity of tastants has led to the need for multiple transduction mechanisms. Through molecular cloning and data mining, many of the receptors, G proteins, and effector enzymes involved in transducing responses to bitter and sweet compounds are now known. New insights into taste transduction and taste coding underlying sweet and bitter taste qualities have been gained from molecular cloning of the transduction elements, biochemical elucidation of the transduction pathways, electrophysiological analysis of the function of taste cell ion channels, and behavioral analysis of transgenic and knockout models.