title: Neoculin, a taste-modifying protein, is recognized by human sweet taste receptor.
abstract: Neoculin, a sweet protein occurring in Curculigo latifolia, is unique in that it also has taste-modifying activity capable of converting sourness to sweetness. Calcium imaging analysis with HEK cells expressing the human sweet taste receptor, hT1R2/T1R3 demonstrated that the intracellular calcium concentration increased following the addition of 20 microM neoculin. The use of lactisole, a blocker of hT1R3, inhibited the intracellular calcium concentration increase almost completely. In sensory tests, when acetate buffers with different pH values were placed on the tongue after tasting neoculin, a higher intensity of sweetness was detected at lower pH. The sweetness was also suppressed with the addition of lactisole. These results suggest that both the sweetness and the taste-modifying activity are mediated via the human sweet taste receptor.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan.
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Nakajima
authors.forename: Tomiko
authors.initials: T
authors.lastname: Asakura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Oike
authors.forename: Yuji
authors.initials: Y
authors.lastname: Morita
authors.forename: Akiko
authors.initials: A
authors.lastname: Shimizu-Ibuka
authors.forename: Takumi
authors.initials: T
authors.lastname: Misaka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sorimachi
authors.forename: Soichi
authors.initials: S
authors.lastname: Arai
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
mesh_terms: D001555:Benzene Derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010940:Plant Proteins / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D013549:Sweetening Agents / Q000494:pharmacology*; D013649:Taste / Q000187:drug effects*; D014059:Tongue / Q000187:drug effects / Q000502:physiology; D014162:Transfection / Q000379:methods
chemical_list: D001555:Benzene Derivatives; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D013549:Sweetening Agents; C511659:neoculin protein, Curculigo latifolia; C431926:taste receptors, type 1; D002118:Calcium; C495512:lactisole