Crossing the Boundaries of Life

A close look at Gnter Blobels transformative contributions to molecular cell biology. The difficulty of reconciling chemical mechanisms with the functions of whole living systems has plagued biologists since the development of cell theory in the nineteenth century. As Karl S. Matlin argues in Crossing the Boundaries of Life, it is no coincidence that this longstanding knot of scientific inquiry was loosened most meaningfully by the work of a cell biologist, the Nobel laureate Gnter Blobel. In 1975, using an experimental setup that did not contain any cells at all, Blobel was able to target newly made proteins to cell membrane vesicles, enabling him to theorize how proteins in the cell distribute spatially, an idea he called the signal hypothesis. Over the next twenty years, Blobel and other scientists were able to dissect this mechanism into its precise molecular details. For elaborating his signal concept into a process he termed membrane topogenesisthe idea that each protein in the cell is synthesized with an "address" that directs the protein to its correct destination within the cellBlobel was awarded the Nobel Prize in Physiology or Medicine in 1999. Matlin argues that Blobels investigative strategy and its subsequent application addressed a fundamental unresolved dilemma that had bedeviled biology from its very beginningthe relationship between structure and functionallowing biology to achieve mechanistic molecular explanations of biological phenomena. Crossing the Boundaries of Life thus uses Blobels research and life story to shed light on the importance of cell biology for twentieth-century science, illustrating how it propelled the development of adjacent disciplines like biochemistry and molecular biology.