title: Taste-modifying sweet protein, neoculin, is received at human T1R3 amino terminal domain.
abstract: This study examines taste reception of neoculin, a Curculigo latifolia sweet protein with taste-modifying activity which converts sourness to sweetness. Neoculin tastes sweet to humans, but not to mice, and is received by the human sweet taste receptor hT1R2-hT1R3. In the present study with calcium imaging analysis of HEK cells expressing human and mouse T1Rs, we demonstrated that hT1R3 is required for the reception of neoculin. Further experiments using human/mouse chimeric T1R3s revealed that the extracellular amino terminal domain (ATD) of hT1R3 is essential for the reception of neoculin. Although T1R2-T1R3 is known to have multiple potential ligand-binding sites to receive a wide variety of sweeteners, the present study is apparently the first to identify the ATD of hT1R3 as a new sweetener-binding region.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Koizumi
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Nakajima
authors.forename: Tomiko
authors.initials: T
authors.lastname: Asakura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Morita
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ito
authors.forename: Akiko
authors.initials: A
authors.lastname: Shmizu-Ibuka
authors.forename: Takumi
authors.initials: T
authors.lastname: Misaka
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry* / Q000378:metabolism*; D013549:Sweetening Agents / Q000737:chemistry / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D013549:Sweetening Agents; C511659:neoculin protein, Curculigo latifolia; C431926:taste receptors, type 1