Günter Blobel (1936- present) was awarded the 1999 Nobel Prize in Physiology or Medicine for the discovery that proteins have intrinsic signals that govern their transport and localization in the cell. Blobel established the general principles underlying the mechanism by which proteins are targeted to specific organelles within a cell. Blobel and colleagues showed that each protein carries a signal sequence that directs it to a specific location within the cell. The signal sequence, which consists of several 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 pore-like 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.