title: The cysteine-rich domain of human T1R3 is necessary for the interaction between human T1R2-T1R3 sweet receptors and a sweet-tasting protein, thaumatin.
abstract: Thaumatin is an intensely sweet-tasting protein perceived by humans but not rodents. Its threshold value of sweetness in humans is 50nM, the lowest of any sweet-tasting protein. In the present study, the sites where sweet receptors interact with thaumatin were investigated using human embryonic kidney 293 (HEK293) cells expressing the sweet receptors T1R2-T1R3. Chimeric human- mouse sweet receptors were constructed and their responses to sweeteners were investigated. The human (h) T1R2- mouse (m) T1R3 combination responded to sucralose but not to thaumatin, clearly indicating that a T1R3 subunit from humans is necessary for the interaction with thaumatin. Furthermore, results obtained from using chimeric T1R3s showed that the cysteine-rich domain (CRD) of human T1R3 is important for the interaction with thaumatin. The CRD of T1R3 would be a prominent target for designing new sweeteners.
authors.affiliation: Department of Natural Resources, Graduate School of Global and Environmental Studies, Kyoto University, Japan. k_ooota@kais.kyoto-u.ac.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohta
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Masuda
authors.forename: Fumito
authors.initials: F
authors.lastname: Tani
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kitabatake
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003545:Cysteine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D013649:Taste
chemical_list: D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; C431926:taste receptors, type 1; C003427:thaumatin protein, plant; D003545:Cysteine