Ever tasted the miracle fruit? I haven't, but I really want to. You chew it around in your mouth and for the next hour, sour stuff like lemons taste really, really sweet.
Now researchers in Japan and France have figured out how the fruit plays this trick on us. It involves, not surprisingly, the sweet taste receptor that resides in the membrane of taste bud cells.
Normally, sugars bind to the sweet-taste receptor, as do artificial sweeteners like aspartame, saccharine and sucralose (Splenda). Scientists knew what ingredient in the miracle fruit does this weird thing to our senses: a protein in the fruit dubbed miraculin. But they didn't know how miraculin acted.
Here's how the team, reporting in this week's Proceedings of the National Academy of Sciences, figured it out.
First, they genetically engineered human cells in a dish to carry the sweet taste receptor on their membranes.
Next, they exposed the cells to miraculin and let things sit awhile.
They acidified the solution in which the cells were bathed -- much as the saliva in your mouth would be acidified if you bit into a pickle or chewed on a lemon slice. Now they could see that the sweet-taste receptors became active.