The cysteine-rich domain of human T1R3 is necessary for the interaction between human T1R2-T1R3 sweet receptors and a sweet-tasting protein, thaumatin

Biochem Biophys Res Commun. 2011 Mar 18;406(3):435-8. doi: 10.1016/j.bbrc.2011.02.063. Epub 2011 Feb 15.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cysteine / chemistry
  • Cysteine / genetics
  • Cysteine / metabolism
  • HEK293 Cells
  • Humans
  • Mice
  • Molecular Sequence Data
  • Plant Proteins / metabolism*
  • Protein Structure, Tertiary
  • Receptors, G-Protein-Coupled / chemistry
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Taste*


  • Plant Proteins
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins
  • taste receptors, type 1
  • thaumatin protein, plant
  • Cysteine