Abstract
Although the five basic taste qualities—sweet, sour, bitter, salty and umami—can be recognized by the respective gustatory system, interactions between these taste qualities are often experienced when food is consumed. Specifically, the umami taste has been investigated in terms of whether it enhances or reduces the other taste modalities. These studies, however, are based on individual perception and not on a molecular level. In this study we investigated umami-sweet taste interactions using umami compounds including monosodium glutamate (MSG), 5’-mononucleotides and glutamyl-dipeptides, glutamate-glutamate (Glu-Glu) and glutamate-aspartic acid (Glu-Asp), in human sweet taste receptor hT1R2/hT1R3-expressing cells. The sensitivity of sucrose to hT1R2/hT1R3 was significantly attenuated by MSG and umami active peptides but not by umami active nucleotides. Inhibition of sweet receptor activation by MSG and glutamyl peptides is obvious when sweet receptors are activated by sweeteners that target the extracellular domain (ECD) of T1R2, such as sucrose and acesulfame K, but not by cyclamate, which interact with the T1R3 transmembrane domain (TMD). Application of umami compounds with lactisole, inhibitory drugs that target T1R3, exerted a more severe inhibitory effect. The inhibition was also observed with F778A sweet receptor mutant, which have the defect in function of T1R3 TMD. These results suggest that umami peptides affect sweet taste receptors and this interaction prevents sweet receptor agonists from binding to the T1R2 ECD in an allosteric manner, not to the T1R3. This is the first report to define the interaction between umami and sweet taste receptors.
Highlights
Most food products comprise of multiple mixtures of tastants
Umami compounds influenced the response of sweet receptor cells to sucrose To examine interaction between sweet and umami taste signaling at the receptor level, we evaluated the response of sweet receptor cells after treatment with various combinations of umami compounds and sucrose
When monosodium glutamate (MSG) was co-applied with sucrose, the induced response of sweet receptor cells by sucrose was attenuated (Fig 1A)
Summary
Most food products comprise of multiple mixtures of tastants. Animals integrate and unify the information regarding each separate taste and decide on their feeding behavior. Modulation of Sweet Taste by Umami Compounds has focused on and described the interactions between taste modalities [1,2,3,4]. These studies are restricted to observations of phenotype and phenomenon and the detailed molecular and cellular mechanisms have not been fully investigated. These interactions occur at the level of neuronal transduction and at level of taste receptor [5, 6]. A recent study revealed that binding of amiloride, a type of salt sensing reducer, to sweet receptors inhibited their responses [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
