title: Structure, function, and signaling of taste G-protein-coupled receptors.
abstract: 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.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sanematsu
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Yoshida
authors.forename: Noriatsu
authors.initials: N
authors.lastname: Shigemura
authors.affiliation: Section of Oral Neuroscience, Graduate School of Dental Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. sanematu@dent.kyushu-u.ac.jp.
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Ninomiya
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000378:metabolism
chemical_list: D043562:Receptors, G-Protein-Coupled