title: Functional characterization of the heterodimeric sweet taste receptor T1R2 and T1R3 from a New World monkey species (squirrel monkey) and its response to sweet-tasting proteins.
abstract: The family C G protein-coupled receptor (GPCR) T1R2 and T1R3 heterodimer functions as a broadly acting sweet taste receptor. Perception of sweet taste is a species-dependent physiological process. It has been widely reported that New World monkeys and rodents are not able to perceive some of the artificial sweeteners and sweet-tasting proteins that can be perceived by humans, apes, and Old World monkeys. Until now, only the sweet receptors of humans, mice and rats have been functionally characterized. Here we report characterization of the sweet taste receptor (T1R2/T1R3) from a species of New World primate, squirrel monkey. Our results show that the heterodimeric receptor of squirrel monkey does not respond to artificial sweeteners aspartame, neotame, cyclamate, saccharin and sweet-tasting protein monellin, but surprisingly, it does respond to thaumatin at high concentrations (>18 μM). This is the first report demonstrating that species of New World monkey can perceive some specific sweet-tasting proteins. Furthermore, the sweet receptor of squirrel monkey responses to the such sweeteners cannot be inhibited by the sweet inhibitor lactisole. We compared the response differences of the squirrel monkey and human receptors and found that the residues in T1R2 determine species-dependent sweet taste toward saccharin, while the residues in either T1R2 or T1R3 are responsible for the sweet taste difference between humans and squirrel monkeys toward monellin. Molecular models indicated that electrostatic properties of the receptors probably mediate the species-dependent response to sweet-tasting proteins.
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, 1220 East Broad Street, P.O. Box 980551, Richmond, VA 23298, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Matthew
authors.initials: M
authors.lastname: Ha
authors.forename: Xuan-Yu
authors.initials: XY
authors.lastname: Meng
authors.forename: Mohammed
authors.initials: M
authors.lastname: Khaleduzzaman
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Meng
authors.initials: M
authors.lastname: Cui
mesh_terms: D000818:Animals; D001218:Aspartame / Q000737:chemistry / Q000494:pharmacology; D001555:Benzene Derivatives / Q000494:pharmacology; D006801:Humans; D010940:Plant Proteins / Q000737:chemistry* / Q000494:pharmacology; D011487:Protein Conformation; D055503:Protein Multimerization; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry* / Q000502:physiology*; D012439:Saccharin / Q000737:chemistry / Q000494:pharmacology; D012453:Saimiri / Q000502:physiology*; D055672:Static Electricity; D013549:Sweetening Agents / Q000737:chemistry* / Q000494:pharmacology; D013649:Taste / Q000187:drug effects / Q000502:physiology*; D055697:Taste Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D001555:Benzene Derivatives; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D013549:Sweetening Agents; C002541:monellin protein, Dioscoreophyllum cumminsii; C431926:taste receptors, type 1; C003427:thaumatin protein, plant; D012439:Saccharin; D001218:Aspartame; C495512:lactisole