Multiple Umami Receptors and Their Variants in Human and Mice

Abstract

L-Glutamate and 5 -ribonucleotides are known to elicit a unique taste, "umami," that is distinct from the tastes of sweet, salt, sour and bitter. Recent progress in molecular biology has identified several umami receptor candidates, such as the heterodimer T1R1/T1R3, and brain-expressed and taste-expressed type 1 and 4 metabotropic glutamate receptors (brain-and taste-mGluR1 and mGluR4). This paper summarizes recent findings on the receptor system for umami taste. Most of the findings support the idea that multiple receptors exist for umami taste, at least in mice. The accumulating evidence indicates that the potential role of the signal mediated by the transduction pathway involving T1R1/T1R3 may be different from that mediated by the pathway involving mGluRs. The former signal occurs mainly in the anterior tongue, and plays a major role in preference behavior, whereas the latter occurs mainly in the posterior tongue, is active in mice lacking T1R3, Gα-gustducin, IP 3 R3 or TRPM5, and contributes to behavioral discrimination between umami and other taste compounds. In humans, unlike in mice, T1R1/T1R3 acts as an umami-specific receptor that can discriminate between umami and other tastes, and thus account for umami-linked preferences or discrimination.

Expression of umami‐taste‐related genes in the tongue: a pilot study for genetic taste diagnosis

“…Additionally, the human T1R1/T1R3 exhibits potentiation of the response to the amino acid, glutamate, by addition of inosine monophosphate, which is the most characteristic feature of the umami taste (a synergistic taste effect) (Yamaguchi, ). Our results may be in accordance with those of previous basic science reports, indicating that human T1R1/T1R3 acts as an umami‐taste‐specific receptor that can discriminate between umami and other tastes (Jyotaki et al , ). Furthermore, in the present study, stimulation of the tongue mucosa by MSG upregulated the gene expression of T1R1 and T1R3 (Figure a,b), but not of mGluR1 (Figure c).…”

“…This difference in frequency implies that T1R1/T1R3 is the predominant receptor for human umami sensation. In mice, mGluRs have been reported to be involved in the detection of umami compounds (Kusuhara et al , ), and the signal mediated by the mGluRs pathway, mainly in the posterior tongue, contributes to behavioural discrimination between the umami taste and other taste compounds (Jyotaki et al , ). However, the roles of mGluRs have not been clarified in humans.…”

Seaweeds for umami flavour in the New Nordic Cuisine

“…Since then, two other umami receptors have been found: T1R1/T1R3 [24,25] and a special mGlu receptor [26] that is related to the brain glutamate receptor mGluR1. It remains unclear whether the different umami receptors use different signalling pathways [27,28].…”

Umami taste (sodium glutamate sensitivity) thresholds at gustometry in various variants of bronchial asthma

“…Прежде, чем обсуждать выявленный нами феномен существенно более высокой вкусовой чувствительности больных с аллергическим вариантом бронхиальной астмы к лиганду умами-рецепторов (глутамату натрия), отметим, что к настоящему времени выявлена экспрессия следующих глутаматных рецепторов: сопряженные с G-белком Tas1R1/Tas1R3, mGluR1 и mGluR4, а также ионотропные глутамат-зависимые ионные каналы, в частности, NMDA (N-метил-Dаспартат)-рецептор [13]. При этом за вкус умами отвечают главным образом рецепторы Tas1R1/ Tas1R3 [14].…”