title: The receptors for mammalian sweet and umami taste.
abstract: Sweet and umami (the taste of monosodium glutamate) are the main attractive taste modalities in humans. T1Rs are candidate mammalian taste receptors that combine to assemble two heteromeric G-protein-coupled receptor complexes: T1R1+3, an umami sensor, and T1R2+3, a sweet receptor. We now report the behavioral and physiological characterization of T1R1, T1R2, and T1R3 knockout mice. We demonstrate that sweet and umami taste are strictly dependent on T1R-receptors, and show that selective elimination of T1R-subunits differentially abolishes detection and perception of these two taste modalities. To examine the basis of sweet tastant recognition and coding, we engineered animals expressing either the human T1R2-receptor (hT1R2), or a modified opioid-receptor (RASSL) in sweet cells. Expression of hT1R2 in mice generates animals with humanized sweet taste preferences, while expression of RASSL drives strong attraction to a synthetic opiate, demonstrating that sweet cells trigger dedicated behavioral outputs, but their tastant selectivity is determined by the nature of the receptors.
authors.affiliation: Howard Hughes Medical Institute and Departments of Biology and Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA.
authors.forename: Grace Q
authors.initials: GQ
authors.lastname: Zhao
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hoon
authors.forename: Jayaram
authors.initials: J
authors.lastname: Chandrashekar
authors.forename: Isolde
authors.initials: I
authors.lastname: Erlenbach
authors.forename: Nicholas J P
authors.initials: NJ
authors.lastname: Ryba
authors.forename: Charles S
authors.initials: CS
authors.lastname: Zuker
mesh_terms: D000818:Animals; D005421:Flavoring Agents / Q000378:metabolism / Q000494:pharmacology; D017353:Gene Deletion; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D017473:Receptors, Opioid, kappa / Q000235:genetics / Q000378:metabolism; D012970:Sodium Glutamate / Q000378:metabolism / Q000494:pharmacology; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology; D013649:Taste / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013650:Taste Buds / Q000187:drug effects / Q000378:metabolism
chemical_list: D005421:Flavoring Agents; D020033:Protein Isoforms; D021122:Protein Subunits; D043562:Receptors, G-Protein-Coupled; D017473:Receptors, Opioid, kappa; C110260:Ro1 protein, synthetic; C431926:taste receptors, type 1; D013395:Sucrose; D012970:Sodium Glutamate