Detection of tastes is critical for animals. Sweet, umami and bitter taste are mediated by G-protein-coupled receptors
that are expressed in the taste receptor cells. TAS1Rs which belong to class C G-protein-coupled receptors form
heterodimeric complexes to function as sweet (TAS1R2 + TAS1R3) or umami (TAS1R1 + TAS1R3) taste receptors. Umami
taste is also considered to be mediated by mGluRs. TAS2Rs belong to class A G-protein-coupled receptors and are
responsible for bitter taste. After activation of these receptors, their second messenger pathways lead to depolarization and
intracellular calcium increase in taste receptor cells. Then, transmitter is released from taste receptor cells leading to activation
of taste nerve fibers and taste information is sent to the central nervous system. Recent studies on heterologous expression
system and molecular modeling lead to better understanding of binding site of TAS1Rs and TAS2Rs and molecular
mechanisms for interaction between taste substances and these receptors. TAS1Rs and TAS2Rs have multiple and
single binding sites for structurally diverse ligands, respectively. Sensitivities of these receptors are known to differ among
individuals, strains, and species. In addition, some species abolish these receptors and signaling molecules. Here we focus on
structure, function, signaling, polymorphism, and molecular evolution of the taste G-protein-coupled receptors.
Keywords: Bitter taste, G-protein-coupled receptors, molecular evolution, molecular modeling, signal transduction, sweet
taste, TAS1Rs, TAS2Rs, umami taste.
Rights & PermissionsPrintExport