抄録
Umami is a taste quality exemplified by taste of MSG and evoked also by some amino acids and purine nucleotides. There is an evidence that a heterodimer of T1r1 and T1r3 proteins functions as an umami taste receptor in humans and rodents. A splice variants of a metabotropic glutamate receptor, mGluR1 and mGluR4, were also proposed as a taste receptor for glutamate. Taste sensitivity to umami substances varies among individual humans. However, little is known about association of genetic variation with umami taste responses in both human and rodents. In this study, therefore, we investigated possible relationships of individual differences in umami sensitivity with single nucleotide polymorphisms (SNPs) of T1r1, T1r3 in human. The working sample consists of non-obese 200 adults of both sexes (110 men, 90 women), aged 19-35. Taste recognition thresholds for MSG, IMP and MSG plus 0.5 mM IMP were determined by blind-test, series of graded aqueous solutions of each product. Distributions of MSG and IMP taste recognition thresholds showed a normal distribution curve, while, that for MSG plus IMP showed a tri-modal distribution curve. In sequencing analysis, 5 SNPs (amino acid positions: E12H, T139M, N191S, E347K, T372A) and 3 SNPs (T716K, R757C, R825S) with amino acid substitutions were identified in T1r1 and T1r3, respectively. We have analyzed the detail association between a diversity of umami sensitivity and these SNPs. [J Physiol Sci. 2008;58 Suppl:S169]
