Journal Article

Molecular Mechanism for the Umami Taste Synergism

Klebansky, Boris, Fine, Richard M., Xu, Hong, Li, Xiaodong, Tachdjian, Catherine, Pronin, Alexey, Liu, Haitian, Zhang, Feng

2008

Overview

Umami is one of the 5 basic taste qualities. The umami taste of L-glutamate can be drastically enhanced by 5' ribonucleotides and the synergy is a hallmark of this taste quality. The umami taste receptor is a heteromeric complex of 2 class C G-protein-coupled receptors, T1R1 and T1R3. Here we elucidate the molecular mechanism of the synergy using chimeric T1R receptors, site-directed mutagenesis, and molecular modeling. We propose a cooperative ligand-binding model involving the Venus flytrap domain of T1R1, where L-glutamate binds close to the hinge region, and 5' ribonucleotides bind to an adjacent site close to the opening of the flytrap to further stabilize the closed conformation. This unique mechanism may apply to other class C G-protein-coupled receptors.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Binding sites / Binding Sites - physiology / Biological Sciences / Cell Line / Cell lines / chimerism / Dionaea muscipula / Dose response relationship / glutamic acid / Glutamic Acid - chemistry / Glutamic Acid - genetics / Glutamic Acid - metabolism / HEK293 cells / Humans / Ligands / Metabotropic glutamate receptors / Models, Molecular / Molecular biology / molecular models / Multiprotein Complexes - chemistry / Multiprotein Complexes - genetics / Multiprotein Complexes - metabolism / Mutagenesis / Mutagenesis, Site-Directed / Protein Binding - physiology / Protein Structure, Quaternary - physiology / Receptors / Receptors, G-Protein-Coupled - chemistry / Receptors, G-Protein-Coupled - genetics / Receptors, G-Protein-Coupled - metabolism / ribonucleotides / Ribonucleotides - chemistry / Ribonucleotides - genetics / Ribonucleotides - metabolism / site-directed mutagenesis / Sweeteners / Synergism / Taste / Taste - physiology / taste receptors / Umami