Human sweet taste receptor mediates acid-induced sweetness of miraculin

• DOI: 10.1073/pnas.1016644108
• Publication Date: 2011-09-27T06:26:14Z
• Authors: Ayako Koizumi; Asami Tsuchiya; Ken-ichiro Nakajima; Keisuke Ito; Tohru Terada; Akiko Shimizu-Ibuka; Loïc Briand; Tomiko Asakura; Takumi Misaka; Keiko Abe
• Keywords: Sweetness; Sweet Taste; Taste receptor

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 sweetness. Once MCL held on tongue, strong sweetness sensed over 1 h each time we solution. Nevertheless, no molecular mechanism underlying been clarified. In this study, succeeded quantitatively evaluating acid-induced using cell-based assay system and found that activated hT1R2-hT1R3 pH-dependently as pH decreased 6.5 4.8, receptor activation occurred every an acid solution was applied. Although per se sensory-inactive 6.7 or higher, it suppressed response other sweeteners enhanced weakly acidic pH. Using human/mouse chimeric receptors modeling, revealed amino-terminal domain hT1R2 required for MCL. Our data suggest binds antagonist functionally changes into agonist conclude may cause its activity.