Prize committee said in a statement the 8 million crown ($1.2 million) prize went to the American duo for discovering the inner workings of G-protein-coupled receptors.
"Around half of all medications act through these receptors, among them beta blockers, anti-histamines and various kinds of psychiatric medications," the committee said. Working out better ways to target the receptors, known as GPCRs, is an area of keen focus for pharmaceutical and biotechnology companies.
Lefkowitz told a news conference by telephone that he was asleep when the phone call came from Sweden. "I did not hear it - I must share with you that I wear earplugs to sleep. So my wife gave me an elbow. So there it was, a total shock and surprise," he said.
Sven Lidin, Professor of Inorganic Chemistry at Lund University and chairman of the committee, told a news conference the discovery had been key in medical research.
"Knowing what they (the receptors) look like and how they function will provide us with the tools to make better drugs with fewer side effects," he added. Chemistry was the third of this year's Nobel prizes. Prizes for achievements in science, literature and peace were first awarded in 1901 in accordance with the will of dynamite inventor and businessman Alfred Nobel.