The Nobel prize for medicine honored breakthroughs in understanding how key substances are moved around within a cell. Each cell is a factory that produces and exports molecules. For instance, insulin is manufactured and released into the blood and signaling molecules called neurotransmitters are sent from one nerve cell to another. That process happens through vesicles, tiny bubbles that deliver their cargo within a cell to the right place at the right time. Disturbances in the delivery system can lead to neurological diseases, diabetes or immunological disorders.
What did each Nobel laureate contribute to the understanding of vesicles? Here is more detail from the official site of the Nobel Prize on what each laureate contributed to the field.
- Randy Schekman (Yale University): Discovered a set of genes that were required for vesicle traffic. In a genetic screen, he identified yeast cells with defective transport machinery, giving rise to a situation resembling a poorly planned public transport system. Vesicles piled up in certain parts of the cell. He found that the cause of this congestion was genetic and went on to identify the mutated genes.
- James Rothman (University of California, Berkeley): Unravelled protein machinery that allows vesicles to fuse with their targets to permit transfer of cargo. When studying vesicle transport in mammalian cells in the 1980s and 1990s, Rothman discovered that a protein complex enables vesicles to dock and fuse with their target membranes. In the fusion process, proteins on the vesicles and target membranes bind to each other like the two sides of a zipper. The fact that there are many such proteins and that they bind only in specific combinations ensures that cargo is delivered to a precise location.
- Thomas Südhof (Stanford University): Revealed how signals instruct vesicles to release their cargo with precision. The signalling molecules, neurotransmitters, are released from vesicles that fuse with the outer membrane of nerve cells by using the machinery discovered by Rothman and Schekman. But these vesicles are only allowed to release their contents when the nerve cell signals to its neighbours…Calcium ions were known to be involved in this process and in the 1990s, Südhof searched for calcium sensitive proteins in nerve cells. He identified molecular machinery that responds to an influx of calcium ions and directs neighbour proteins rapidly to bind vesicles to the outer membrane of the nerve cell. The zipper opens up and signal substances are released. Südhof´s discovery explained how temporal precision is achieved and how vesicles´ contents can be released on command