start-ver=1.4
cd-journal=joma
no-vol=19
cd-vols=
no-issue=3
article-no=
start-page=e0300981
end-page=
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2024
dt-pub=20240322
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Chemical range recognized by the ligand-binding domain in a representative amino acid-sensing taste receptor, T1r2a/T1r3, from medaka fish
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Taste receptor type 1 (T1r) proteins are responsible for recognizing nutrient chemicals in foods. In humans, T1r2/T1r3 and T1r1/T1r3 heterodimers serve as the sweet and umami receptors that recognize sugars or amino acids and nucleotides, respectively. T1rs are conserved among vertebrates, and T1r2a/T1r3 from medaka fish is currently the only member for which the structure of the ligand-binding domain (LBD) has been solved. T1r2a/T1r3 is an amino acid receptor that recognizes various l-amino acids in its LBD as observed with other T1rs exhibiting broad substrate specificities. Nevertheless, the range of chemicals that are recognized by T1r2a/T1r3LBD has not been extensively explored. In the present study, the binding of various chemicals to medaka T1r2a/T1r3LBD was analyzed. A binding assay for amino acid derivatives verified the specificity of this protein to l-alpha-amino acids and the importance of alpha-amino and carboxy groups for receptor recognition. The results further indicated the significance of the alpha-hydrogen for recognition as replacing it with a methyl group resulted in a substantially decreased affinity. The binding ability to the protein was not limited to proteinogenic amino acids, but also to non-proteinogenic amino acids, such as metabolic intermediates. Besides l-alpha-amino acids, no other chemicals showed significant binding to the protein. These results indicate that all of the common structural groups of alpha-amino acids and their geometry in the l-configuration are recognized by the protein, whereas a wide variety of alpha-substituents can be accommodated in the ligand binding sites of the LBDs.
en-copyright=
kn-copyright=

en-aut-name=IshidaHikaru
en-aut-sei=Ishida
en-aut-mei=Hikaru
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=YasuiNorihisa
en-aut-sei=Yasui
en-aut-mei=Norihisa
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=YamashitaAtsuko
en-aut-sei=Yamashita
en-aut-mei=Atsuko
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

affil-num=1
en-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
kn-affil=

affil-num=2
en-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
kn-affil=

affil-num=3
en-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
kn-affil=
END