The Gene: An Intimate History

by Siddhartha Mukherjee

The paucity of medicines has one principal reason: specificity. Nearly every drug works by binding to its target and enabling or disabling it—turning molecular switches on or off. To be useful, a drug must bind to its switches—but to only a selected set of switches; an indiscriminate drug is no different from a poison. Most molecules can barely achieve this level of discrimination—but proteins have been designed explicitly for this purpose. Proteins, recall, are the hubs of the biological world. They are the enablers and the disablers, the machinators, the regulators, the gatekeepers, the operators, of cellular reactions. They are the switches that most drugs seek to turn on and off. Proteins are thus poised to be some of the most potent and most discriminating medicines in the pharmacological world. But to make a protein, one needs its gene—and here recombinant DNA technology provided the crucial missing stepping-stone. The cloning of human genes allowed scientists to manufacture proteins—and the synthesis of proteins opened the possibility of targeting the millions of biochemical reactions in the human body. Proteins made it possible for chemists to intervene on previously impenetrable aspects of our physiology. The use of recombinant DNA to produce proteins thus marked a transition not just between one gene and one medicine, but between genes and a novel universe of drugs.