BLOBEL, GNTER

born May 21, 1936, Waltersdorf, Silesia, Ger. [now Niegoslawice, Pol.] German-born cellular and molecular biologist who was awarded the Nobel Prize for Physiology or Medicine in 1999 for his discovery that proteins have signals that govern their movement and position in the cell. Blobel received a medical degree at Eberhard-Karl University of Tbingen, Germany, in 1960 and in 1967 earned a Ph.D. in oncology at the University of Wisconsin. That year he joined the Rockefeller University protein laboratory in New York City, then led by George Palade, and in 1976 became a professor at the university. At Rockefeller, Blobel began studying the transport and localization of proteins in cells. There are about one billion protein molecules in a cell, and they perform a wide variety of specific functions. Some are used inside cells as structural material for building new cell components, while others serve as enzymes that speed up biochemical reactions. Still others must be transported to the cell membrane so they can be exported outside the cell to circulate in the blood to other parts of the body. For two decades, however, scientists did not understand two critical details of protein processing: how newly produced proteins are routed to their correct location in the cell, and how proteins pass through the tightly celled membrane that surrounds each organelle. By 1980 Blobel had established the general principles underlying the mechanism by which proteins are targeted to specific organelles within a cell. Working in collaboration with other research groups, he conducted a series of experiments that showed that each protein carries an address code within its molecular structure, a signal sequence that directs it to the proper locale inside the cell. The address code, which consists of a sequence of amino acids, specifies whether the protein will pass through the membrane of a specific organelle, become integrated into the membrane, or be exported out of the cell. Blobel also concluded that proteins enter organelles through a porelike channel that opens in the organelle's outer membrane when the correct protein arrives at the organelle. Blobel's work shed light on such hereditary diseases as cystic fibrosis and provided the basis for bioengineered drugs, including insulin.