title: Nonsynonymous single nucleotide polymorphisms in human tas1r1, tas1r3, and mGluR1 and individual taste sensitivity to glutamate.
abstract: Several studies indicate an essential role of the heterodimer Tas1R1-Tas1R3 for monosodium l-glutamate (MSG) detection, although others suggest alternative receptors. Human subjects show different taste sensitivities to MSG, and some are unable to detect the presence of glutamate. Our objective was to study possible relations between phenotype (sensitivity to glutamate) and genotype (polymorphisms in candidate glutamate taste receptors tas1r1, tas1r3, mGluR4, and mGluR1) at the individual level. The sensitivity was measured with a battery of tests to distinguish the effect of sodium ions from the effect of glutamate ions in MSG. A total of 142 genetically unrelated white French subjects were categorized into 27 nontasters (specific ageusia), 21 hypotasters, and 94 tasters. Reverse transcriptase polymerase chain reaction and immunohistochemistry showed expression of tas1r1, tas1r3, and alpha-gustducin in fungiform papillae in all 12 subjects tested, including subjects who presented specific ageusia for glutamate. Amplification and sequencing of cDNA and genomic DNA allowed the identification of 10 nonsynonymous single nucleotide polymorphisms (nsSNPs) in tas1r1 (n = 3), tas1r3 (n = 3), and mGluR1 (n = 4). In our sample of subjects, the frequencies of 2 nsSNPs, C329T in tas1r1 and C2269T in tas1r3, were significantly higher in nontasters than expected, whereas G1114A in tas1r1 was more frequent in tasters. These nsSNPs along with minor variants and other nsSNPs in mGluR1, including T2977C, account for only part of the interindividual variance, which indicates that other factors, possibly including additional receptors, contribute to glutamate sensitivity.
authors: NBS-NOPA, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
authors: Mariam
authors: M
authors: Raliou
authors: Anna
authors: A
authors: Wiencis
authors: Anne-Marie
authors: AM
authors: Pillias
authors: Aurore
authors: A
authors: Planchais
authors: Corinne
authors: C
authors: Eloit
authors: Yves
authors: Y
authors: Boucher
authors: Didier
authors: D
authors: Trotier
authors: Jean-Pierre
authors: JP
authors: Montmayeur
authors: Annick
authors: A
authors: Faurion
mesh_terms: D001483:Base Sequence; D005260:Female; D005602:France; D015870:Gene Expression; D005838:Genotype; D006801:Humans; D008297:Male; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D017470:Receptors, Glutamate / Q000235:genetics* / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012970:Sodium Glutamate; D013649:Taste / Q000235:genetics* / Q000502:physiology; D013650:Taste Buds; D013652:Taste Threshold / Q000235:genetics* / Q000502:physiology; D015293:Transducin / Q000378:metabolism
chemical_list: D043562:Receptors, G-Protein-Coupled; D017470:Receptors, Glutamate; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; C431926:taste receptors, type 1; C075192:gustducin; D015293:Transducin; D012970:Sodium Glutamate; C108823:metabotropic glutamate receptor 4