Vaults: the hollow barrels inside your cells (Video)

0:00 Vaults: the hollow barrels inside your cells

As a biologist, this one blew my mind. A typical cell in your body may hold about 10,000 tiny hollow barrels made of protein called vaults. Scientists found them 40 years ago, and they're still trying to work out what they do. Stay to the end because the strangest part is what's hiding inside. In 1986, Nancy Kedersha and Leonard Rome found them in rat liver under the electron microscope. The ribs on the shell reminded them of a cathedral ceiling, which is where the name comes from. Each vault is built from 78 copies of the same protein in two halves that meet at the waist. A vault is about 67 nanometers long and 40 wide, bigger than a ribosome. For 40 years, scientists have been guessing at what vaults do. They may carry cargo in and out of the nucleus, help a cell handle toxins, or play a part in immunity. But so far, none of them has been confirmed. You can even breed mice with no vaults at all, and the mice survive. This week, a team at Anthropic, working with their AI model, Claude, searched about 15 billion proteins. They found relatives of the vault protein in 29 bacterial phyla, four archaeal phyla, and the viruses that infect bacteria, though in fewer than one in 100 species. The team made some of these proteins in E. coli. Seven built particles that looked like vaults and four were confirmed as real vaults. Purifying them used to take about 3 days and they got it down to about 90 minutes. To see one up close, they froze the particles in thin ice and took pictures with an electron microscope. Software combined those pictures into a 3D model with a resolution of 3.2 angstroms. The structure came from a phage protein they call L05. Our vaults use 78 copies of their protein. L05 uses 96 with 48 in each half, about 9.5 megadaltons in all. Size matters because a vault is a container. L05 holds about a quarter more space than a human vault. When the team added two extra wall segments, the vault grew by about 20%. Now for the strangest part. Each of those 96 copies has a small pocket with a molecule sitting inside. A search of 25,000 molecules points to coenzyme A, a common helper molecule. The team can't say for sure yet, but if it holds up, it could be a first clue to what vaults do. We should be careful, though. These vaults were made in lab-grown E. coli, not in their natural hosts, and the report has not been peer-reviewed. Vaults reach far deeper into the tree of life than we knew. And after 40 years, their job is still an open question.