Receptor, signal transduction and evolution of sweet, umami and bitter taste

Abstract

Like olfaction, the sense of taste allows the detection and discrimination of chemicals in the environment. However, while olfaction is specialized in the detection of volatile chemicals, taste is restricted to the detection of contact-chemicals. Two families of mammalian taste receptors, T1R and T2R, involved in recognition of sweet, umami (the taste of monosodium glutamate) and bitter stimuli have been identified and characterized. Although much progress has been made in studies on the basic mechanisms of taste recognition and signal transduction in mammals, we are still far from a full understanding of different taste qualities. This review presents a current perspective on sweet, bitter and umami taste receptors and their signal transduction mechanism. We also discuss the evolution of taste and taste-related molecules.

Identification of novel umami molecules via QSAR models and molecular docking

“…22 The extracellular domain structures of the sweet and bitter taste receptors consist of multiple rings and cavities, which play essential roles in ligand recognition. 11 In the current study, 169 candidate umami molecules with bitter and sweet taste receptors were docked to verify the authenticity of forecasting results. The heterodimer T1R2/T1R3, which binds to sweet substances, has a Venus Fly Trap domain that is considered a ligand-binding domain activated by most sweet substances.…”

“…10 Similar to the mechanism of sweet and bitter transduction, umami transduction also involves binding taste-presenting substances to specific taste receptors on the taste cell plasma membrane. 11 The umami, sweet, and bitter taste receptors have a complex relationship. All of these receptors are structurally mediated by G protein-coupled receptors, known as the seven transmembrane receptors, whose common feature is the presence of seven α-helical trans-membrane domains with three extracellular and three intracellular loops.…”

Sweet Chestnut (Castanea sativa Mill.) Nutritional and Phenolic Composition Interactions with Chestnut Flavor Physiology

“…Sweetness detection in the oral cavity of the taster occurs in type II cells and is mediated by a heterodimer receptor called T1R2/T1R3 that is coupled to the G protein superfamily [ 44 , 62 , 63 , 65 , 66 ]. The transduction mechanism of the umami taste modality is very similar to the sweet-taste mechanism [ 67 , 68 , 69 ]. The prominent taste receptor is also a heterodimer belonging to the G-protein coupled receptors but formed by T1R1/T1R3 proteins [ 44 , 64 , 68 , 70 , 71 ].…”

“…The transduction mechanism of the umami taste modality is very similar to the sweet-taste mechanism [ 67 , 68 , 69 ]. The prominent taste receptor is also a heterodimer belonging to the G-protein coupled receptors but formed by T1R1/T1R3 proteins [ 44 , 64 , 68 , 70 , 71 ]. Several studies have revealed that medium/high concentrations of monosodium glutamate increase the perception of salty taste, modulate that of sweet taste, and suppress the perception of sour and bitter tastes [ 71 , 72 ].…”

“…As with the elemental sweet and umami tastes, the transduction mechanism of the bitter taste is mediated by receptors that belong to the family of taste receptors coupled to the G protein and that are identified in type II receptor cells. In humans, and in particular, for bitter tastes, this family of receptors is composed of about 25 receptors that are called “Taste Receptor Family 2”—T2Rs [ 68 , 73 , 74 , 75 , 76 , 77 , 78 ]. As with the elemental sweet and umami tastes, the interaction between the receptor and, subsequently, the G-protein is critical for an increase in PLCβ2 activity and, consequently, the IP3R3 receptor to be activated; an event that mediates the release of intracellular Ca 2+ [ 63 , 65 , 66 ].…”