| Human sweet taste receptor mediates acid-induced sweetness of miraculin. | |
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MedLine Citation:
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PMID: 21949380 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Miraculin (MCL) is a homodimeric protein isolated from the red berries of Richadella dulcifica. MCL, although flat in taste at neutral pH, has taste-modifying activity to convert sour stimuli to sweetness. Once MCL is held on the tongue, strong sweetness is sensed over 1 h each time we taste a sour solution. Nevertheless, no molecular mechanism underlying the taste-modifying activity has been clarified. In this study, we succeeded in quantitatively evaluating the acid-induced sweetness of MCL using a cell-based assay system and found that MCL activated hT1R2-hT1R3 pH-dependently as the pH decreased from 6.5 to 4.8, and that the receptor activation occurred every time an acid solution was applied. Although MCL per se is sensory-inactive at pH 6.7 or higher, it suppressed the response of hT1R2-hT1R3 to other sweeteners at neutral pH and enhanced the response at weakly acidic pH. Using human/mouse chimeric receptors and molecular modeling, we revealed that the amino-terminal domain of hT1R2 is required for the response to MCL. Our data suggest that MCL binds hT1R2-hT1R3 as an antagonist at neutral pH and functionally changes into an agonist at acidic pH, and we conclude this may cause its taste-modifying activity. |
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Authors:
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Ayako Koizumi; Asami Tsuchiya; Ken-Ichiro Nakajima; Keisuke Ito; Tohru Terada; Akiko Shimizu-Ibuka; Loïc Briand; Tomiko Asakura; Takumi Misaka; Keiko Abe |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-9-26 |
Journal Detail:
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Title: Proceedings of the National Academy of Sciences of the United States of America Volume: - ISSN: 1091-6490 ISO Abbreviation: - Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-9-27 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7505876 Medline TA: Proc Natl Acad Sci U S A Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Department of Applied Biological Chemistry, and Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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