The Heptahelical Domain of the Sweet Taste Receptor T1R2 Is a New Allosteric Binding Site for the Sweet Taste Modulator Amiloride That Modulates Sweet Taste in a Species-Dependent Manner

The activity of sweet taste receptor (heterodimeric T1R2 and T1R3) can be modulated by sweet regulators. The compound amiloride can inhibit the sweet sensitivity of the human sweet taste receptor. This study describes the species-dependent regulation of the response of sweet taste receptors by this sweet inhibitor. Amiloride inhibited the sweet taste response of humans and mice but not that of squirrel monkeys. Using human/squirrel monkey/mouse chimeric T1R2 and T1R3 receptors as well as the agonist perillartine (which can activate the single heptahelical domain of T1R2), we found that the heptahelical domain of T1R2 is the molecular determinant that mediates the species-dependent sensitivity to this sweet regulator. Compared to the sweet inhibitor lactisole (which acts on T1R3), amiloride has a different allosteric binding site on the sweet receptor, which is important new information for the design of novel sweet taste modulators that act on T1R2.