The receptors for mammalian sweet and umami taste.
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.
Zhao
Grace Q
GQ
Howard Hughes Medical Institute and Departments of Biology and Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA.
Zhang
Yifeng
Y
Hoon
Mark A
MA
Chandrashekar
Jayaram
J
Erlenbach
Isolde
I
Ryba
Nicholas J P
NJ
Zuker
Charles S
CS
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
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