The University of North Carolina at Chapel Hill scientists said their finding has potential implications for drug development since it involves G protein-coupled receptors -- molecules that are the target of 40 percent to 50 percent of modern medicines, such as antihistamines and drugs for high blood pressure.

The study identified the first protein to activate the G-protein signaling pathway from within a cell. In humans, reactions to everything from taste and smell to stimulants such as adrenaline or caffeine requires G-protein signaling.

Discovering a protein that activates G-proteins from inside a cell could open an entirely new pathway for drug development, said Professor Henrik Dohlman, senior study author.

"No drug is 100 percent effective, 100 percent free of side effects and 100 percent safe," said Dohlman. "The more options we have biochemically, the more selective we can be in designing new drugs. If we can find another way of modulating G-proteins, we could expand the drug targets that are available to pharmacology."

The study appears in the journal Current Biology.