Two American scientists win Nobel chemistry prize for understanding how the billions of cells within the human body communicate with the outside world

Robert Lefkowitz and Brian Kobilka won the prize for their pioneering roles in revealing the inner workings of an important family of protein molecules called the G-protein-coupled receptors

Understanding how the billions of cells within the human body communicate with the outside world through changes to the three-dimensional structure of protein molecules has won this year’s Nobel Prize in Chemistry.

Two American scientists will share the 8m Swedish Krona (£750,000) prize for their role in unravelling a key part of the intricate molecular mechanism that allows us to see, smell, feel and respond to changes in the world around us.

Robert Lefkowitz, 69, of the Howard Hughes Medical Institute and Duke University Medical Centre in Durham, North Carolina and Brian Kobilka, 57, of Stanford University School of Medicine in California won the prize for their pioneering roles in revealing the inner workings of an important family of protein molecules called the G-protein-coupled receptors.

It is these proteins that govern the body’s heightened reactions to the sense of fear, such as increased heart rate and muscle tension through the “flight or fight” hormone adrenaline. They are also involved in being able to sense light, odour and flavour, as well as being responsible for allowing about half the drugs currently in use to achieve their desired effects.

Professor Lefkowitz started to investigate the proteins on the surface of cell membranes involved in cell communication in the 1960s with the help of radioactive tags attached to various hormones.

Professor Kobilka made further advances in 1980s when he isolated a gene for one of these protein receptors which turned out to belong to a large family of similar proteins, called the G-protein-coupled receptors. Last year, his work led to the first image of how the 3-D shape of these receptors changes when stimulated by hormones.

Professor Lefkowitz was woken with the news of his Nobel by a phone call from Sweden in the middle of the night at his North Carolina home, which his wife took as he sleep with ear plugs.

“She said, ‘There's a call here for you from Stockholm’,” Lefkowitz told The Associated Press. “I knew they ain't calling to find out what the weather is like in Durham today.”

Professor Kobilka was also asleep when the call from Stockholm came through at 2.30am his time. “They passed the phone around and congratulated me. I guess they do that so you actually believe them. When one person calls you, it can be a joke, but when five people with convincing Swedish accents call you, then it isn't a joke,“ Professor Kobilka said.