Signaling mechanisms controlling taste cell function.

Sensory systems have evolved to collect information about the environment. Each system has developed to gather specific data that are pertinent to an organism's needs, and consequently the systems vary in their abilities to detect external stimuli such as light, sound, vibration, magnetic fields, or chemicals. Although not all sensory systems are present in all organisms, all organisms, even those at the single-cell level, have the ability to detect chemicals in the environment. Chemical detection likely evolved out of organisms' needs to detect food sources and avoid potentially harmful compounds. Higher-level organisms developed two sensory systems to detect environmental chemicals: olfaction and taste. Olfaction is used in many behaviors, such as kin recognition and mate selection, whereas taste is used primarily to determine whether potential food items will be ingested or rejected. The sense of taste involves the detection of five taste qualities: bitter, sweet, salty, sour, and umami, which is the detection of amino acids, specifically glutamate. Because the chemical structures of taste qualities are diverse, numerous mechanisms are used by taste cells to detect these stimuli. This review focuses on our current understanding of the signaling mechanisms used by taste cells to transduce stimulus signals.