Study explains biochemistry of sweet, bitter and savory

Jan. 9 (UPI) -- New research proves that there are at least two proteins vital to tasting sweetness, bitterness and savoriness.

Until now, scientists thought TRPM5 acted alone in facilitating the experience of sweet, bitter and savory foods. But new research shows a second protein, TRPM4, is also essential.

"Our research shows that there is redundancy in the taste system," lead researcher Kathryn Medler, an associate professor of biological sciences at the University at Buffalo, said in a news release. "This is important because taste is actually central to our survival. If you can't taste something bitter, you might gobble up something that's poisonous without ever knowing that it could be harmful."

Medler and her colleagues studied mice as they ate sweet, savory and bitter foods. Mice with TRPM4 eagerly drank sugar water and ate savory snacks, while avoiding bitter quinine. Mice bred without the protein were less able to distinguish between the three flavors.

Researchers published their findings this week in the journal PNAS.

"Our study changes a central dogma in the field -- that detecting bitter, sweet and umami stimuli is dependent on the presence of TRPM5 alone," said first author Debarghya Dutta Banik, a doctoral candidate in biological sciences at Buffalo. "This research helps us understand how the taste system works."

Both the two proteins are ion channels, allowing the reception of flavor compounds to trigger an electrical response that links the tongue and brain and facilitates the flavor experience.

Mice showed the strongest responses to flavor when they possessed both TRPM4 and TRPM5. The same two proteins are found in humans, and researchers think they likely play similar important roles in human taste.

Because taste helps regulate appetite researchers say it's important to understand how the system works. Such research can also help scientists understand how the evolution of taste affected humans and their eating patterns.

"It's important for us to understand how the taste system works," Medler said. "The more we know, the easier it will be to find solutions to problems when the system isn't working correctly."