title: Amino acid residues of bitter taste receptor TAS2R16 that determine sensitivity in primates to β-glycosides.
abstract: In mammals, bitter taste is mediated by TAS2Rs, which belong to the family of seven transmembrane G protein-coupled receptors. Since TAS2Rs are directly involved in the interaction between mammals and their dietary sources, it is likely that these genes evolved to reflect species-specific diets during mammalian evolution. Here, we analyzed the amino acids responsible for the difference in sensitivities of TAS2R16s of various primates using a cultured cell expression system. We found that the sensitivity of TAS2R16 varied due to several amino acid residues. Mutation of amino acid residues at E86T, L247M, and V260F in human and langur TAS2R16 for mimicking the macaque TAS2R16 decreased the sensitivity of the receptor in an additive manner, which suggests its contribution to the potency of salicin, possibly via direct interaction. However, mutation of amino acid residues 125 and 133 in human TAS2R16, which are situated in helix 4, to the macaque sequence increased the sensitivity of the receptor. These results suggest the possibility that bitter taste sensitivities evolved independently by replacing specific amino acid residues of TAS2Rs in different primate species to adapt to species-specific food.
authors.affiliation: Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Imai
authors.affiliation: Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
authors.forename: Nami
authors.initials: N
authors.lastname: Suzuki-Hashido
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Ishimaru
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Sakurai
authors.affiliation: Center for Nature and Society, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Lijie
authors.initials: L
authors.lastname: Yin
authors.affiliation: Center for Nature and Society, School of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Wenshi
authors.initials: W
authors.lastname: Pan
authors.affiliation: Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603, Japan.
authors.forename: Masaji
authors.initials: M
authors.lastname: Ishiguro
authors.affiliation: Suntory Institute for Bioorganic Research, Mishima-gun, Osaka 618-8503, Japan.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Masuda
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Misaka
authors.affiliation: Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Hirai
keywords: G protein-coupled receptor; bitter taste; cell signaling; molecular evolution; primates; receptor regulation