title: Molecular mechanisms of the action of miraculin, a taste-modifying protein.
abstract: Miraculin (MCL) is a homodimeric protein isolated from the fruits of Richadella dulcifica, a shrub native to West Africa. Although it is flat in taste at neutral pH, MCL has taste-modifying activity in which sour stimuli produce a sweet perception. Once MCL enters the mouth, strong sweetness can be detected for more than 1 h each time we taste a sour solution. While the human sweet taste receptor (hT1R2-hT1R3) has been identified, the molecular mechanisms underlying the taste-modifying activity of MCL remain unclear. Recently, experimental evidence has been published demonstrating the successful quantitative evaluation of the acid-induced sweetness of MCL using a cell-based assay system. The results strongly suggested that MCL binds hT1R2-hT1R3 as an antagonist at neutral pH and functionally changes into an agonist at acidic pH. Since sweet-tasting proteins may be used as low-calorie sweeteners because they contain almost no calories, it is expected that MCL will be used in the near future as a new low-calorie sweetener or to modify the taste of sour fruits.
authors: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. amisaka@mail.ecc.u-tokyo.ac.jp
authors: Takumi
authors: T
authors: Misaka
mesh_terms: D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011485:Protein Binding; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D013649:Taste
chemical_list: D006023:Glycoproteins; D043562:Receptors, G-Protein-Coupled; C008533:miraculin protein, Synsepalum dulcificum