Perceptual variation in umami taste and polymorphisms in TAS1R taste receptor genes

• Published in: The American journal of clinical nutrition 2009-09, Vol.90 (3), p.770S-779S
• Main Authors: CHEN, Qing-Ying, ALARCON, Suzanne, THARP, Anilet, AHMED, Osama M, ESTRELLA, Nelsa L, GREENE, Tiffani A, RUCKER, Joseph, BRESLIN, Paul As
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Alleles; Biological and medical sciences; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Genes; Genetic Variation; Genomics; Glutamic Acid; Humans; Inosine Monophosphate; Male; Middle Aged; Polymorphism; Polymorphism, Single Nucleotide; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Receptors, G-Protein-Coupled - physiology; Receptors, Glutamate - genetics; Receptors, Glutamate - physiology; Sensory perception; Studies; T cell receptors; T-Lymphocytes - metabolism; Taste; Taste - genetics; Taste - physiology; Taste Perception - genetics; Taste Perception - physiology; Taste Threshold - genetics; Taste Threshold - physiology; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young Adult
• ISSN: 0002-9165; 1938-3207
• DOI: 10.3945/ajcn.2009.27462n

The TAS1R1 and TAS1R3 G protein-coupled receptors are believed to function in combination as a heteromeric glutamate taste receptor in humans. We hypothesized that variations in the umami perception of glutamate would correlate with variations in the sequence of these 2 genes, if they contribute directly to umami taste. In this study, we first characterized the general sensitivity to glutamate in a sample population of 242 subjects. We performed these experiments by sequencing the coding regions of the genomic TAS1R1 and TAS1R3 genes in a separate set of 87 individuals who were tested repeatedly with monopotassium glutamate (MPG) solutions. Last, we tested the role of the candidate umami taste receptor hTAS1R1-hTAS1R3 in a functional expression assay. A subset of subjects displays extremes of sensitivity, and a battery of different psychophysical tests validated this observation. Statistical analysis showed that the rare T allele of single nucleotide polymorphism (SNP) R757C in TAS1R3 led to a doubling of umami ratings of 25 mmol MPG/L. Other suggestive SNPs of TAS1R3 include the A allele of A5T and the A allele of R247H, which both resulted in an approximate doubling of umami ratings of 200 mmol MPG/L. We confirmed the potential role of the human TAS1R1-TAS1R3 heteromer receptor in umami taste by recording responses, specifically to l-glutamate and inosine 5'-monophosphate (IMP) mixtures in a heterologous expression assay in HEK (human embryonic kidney) T cells. There is a reliable and valid variation in human umami taste of l-glutamate. Variations in perception of umami taste correlated with variations in the human TAS1R3 gene. The putative human taste receptor TAS1R1-TAS1R3 responds specifically to l-glutamate mixed with the ribonucleotide IMP. Thus, this receptor likely contributes to human umami taste perception.