Why are sweet proteins sweet? Interaction of brazzein, monellin and thaumatin with the T1R2-T1R3 receptor.
Sweet tasting proteins interact with the same receptor that binds small molecular weight sweeteners, the T1R2-T1R3 G-protein coupled receptor, but the key groups on the protein surface responsible for the biological activity have not yet been identified. I propose that sweet proteins, contrary to small ligands, do not bind to the 'glutamate-like' pocket but stabilize the free form II of the T1R2-T1R3 receptor by attachment to a secondary binding site. Docking of brazzein, monellin and thaumatin with a model of the T1R2-T1R3 sweet taste receptor shows that the most likely complexes can indeed stabilize the active form of the receptor.
Temussi
Piero Andrea
PA
Computational Biology Unit, EMBL, Heidelberg, Germany. pat@chemistry.unina.it
D029681:Arabidopsis Proteins; D001665:Binding Sites; D002148:Calmodulin-Binding Proteins; D019204:GTP-Binding Proteins / Q000378:metabolism; D018698:Glutamic Acid; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry; D011487:Protein Conformation; D013549:Sweetening Agents; D013649:Taste / Q000502:physiology*
D029681:Arabidopsis Proteins; C434262:BIG protein, Arabidopsis; D002148:Calmodulin-Binding Proteins; D008024:Ligands; D010940:Plant Proteins; D013549:Sweetening Agents; C090521:brazzein protein, Pentadiplandra brazzeana; C002541:monellin protein, Dioscoreophyllum cumminsii; D018698:Glutamic Acid; C003427:thaumatin protein, plant; D019204:GTP-Binding Proteins