When Dr. Robert Lefkowitz began his research career in the late 1960s, it was already known that hormones such as adrenalin, histamine, dopamine and serotonin stimulate specific responses in the cells of human beings and other organisms. But the mechanism by which cells perceive and respond to these hormones was shrouded in mystery.
In 1969, Lefkowitz successfully attached a radioactive isotope of iodine to a form of the hormone ACTH (adrenocorticotrophic hormone), enabling him to demonstrate its receptor's presence in cell membranes from an adrenal cortical tumor. Beginning in the early 1970s he began applying similar methodology to studying the receptors for adrenaline called adrenergic receptors. Over the next 15 years he would identify several different types of adrenergic receptors by utilizing these "radioligand binding techniques." In 1986, he and his associates at Duke University Medical Center succeeded in cloning and sequencing the gene for one of these receptors and found that it responds to adrenaline much as receptors in the eye register light. He has since identified a superfamily of receptor proteins present in the outer membrane of cells.
Roughly half of all medications in use today depend on the action of the receptors Dr. Lefkowitz discovered; they are used to treat everything from diabetes to depression. His discovery has been recognized with nearly every honor in American science, as well as the 2012 Nobel Prize in Chemistry.