Cacao

To demonstrate specificity of the sweet taste receptor, the pathway of G-protein coupled receptors linked to the receptor was modified to increase intracellular calcium which was observed using the fluorescent FURA-2 calcium indicator dye. An increase in cellular calcium was observed (normalized to responses observed from the highest concentration per compound) in the sweet compounds GA-2, saccharin, acesulfame-K, and sucrose in the receptor combination T1R2+3 (Fig 6b), matching the biological thresholds observed in vivo (Fig 6a). Dose responses were not observed for bitter or umami compounds (Fig 6b). As intracellular calcium was not shown to increase upon exposure to any compound other than sugar and artificial sweeteners, the function of T1Rs as a sweet taste receptors is maintained.