title: An amino-acid taste receptor.
abstract: The sense of taste provides animals with valuable information about the nature and quality of food. Mammals can recognize and respond to a diverse repertoire of chemical entities, including sugars, salts, acids and a wide range of toxic substances. Several amino acids taste sweet or delicious (umami) to humans, and are attractive to rodents and other animals. This is noteworthy because L-amino acids function as the building blocks of proteins, as biosynthetic precursors of many biologically relevant small molecules, and as metabolic fuel. Thus, having a taste pathway dedicated to their detection probably had significant evolutionary implications. Here we identify and characterize a mammalian amino-acid taste receptor. This receptor, T1R1+3, is a heteromer of the taste-specific T1R1 and T1R3 G-protein-coupled receptors. We demonstrate that T1R1 and T1R3 combine to function as a broadly tuned L-amino-acid sensor responding to most of the 20 standard amino acids, but not to their D-enantiomers or other compounds. We also show that sequence differences in T1R receptors within and between species (human and mouse) can significantly influence the selectivity and specificity of taste responses.
authors.affiliation: Howard Hughes Medical Institute and Departments of Biology and Neurosciences, University of California at San Diego, La Jolla, California, 92093-0649, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Nelson
authors.forename: Jayaram
authors.initials: J
authors.lastname: Chandrashekar
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hoon
authors.forename: Luxin
authors.initials: L
authors.lastname: Feng
authors.forename: Grace
authors.initials: G
authors.lastname: Zhao
authors.forename: Nicholas J P
authors.initials: NJ
authors.lastname: Ryba
authors.forename: Charles S
authors.initials: CS
authors.lastname: Zuker
mesh_terms: D000483:Alleles; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D002814:Chorda Tympani Nerve / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007291:Inosine Monophosphate / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D009154:Mutation / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics; D021122:Protein Subunits; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013649:Taste / Q000235:genetics / Q000502:physiology; D013650:Taste Buds / Q000737:chemistry; D014162:Transfection
chemical_list: D000596:Amino Acids; D021122:Protein Subunits; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C431926:taste receptors, type 1; D007291:Inosine Monophosphate; D020962:Heterotrimeric GTP-Binding Proteins