A previously unknown component of our cells delivers proteins “like a bike courier in heavy traffic”, according to scientists from the University of Warwick in the UK, and could shed light on the mechanisms that allow cells to spread in diseases such as cancer.
Writing in the Journal of Cell Biology, Stephen Royle and colleagues say the intracellular nanovesicles (INVs) they discovered are the first new vesicles to be identified in 20 years and the smallest known.
“Collectively in the field, we thought we had identified all of the vesicle types that are found in cells,” he says. “It turns out that there was another one and the reason that it’s been missed is because they’re very, very small.
“These vesicles have never been seen before and a lot of people have focused on other vesicles, such as the long tubules in cells. But we know that when proteins reach the cell’s surface they’re not delivered in a big tube, it’s something smaller. We think it’s these INVs.”
The team only spotted the tiny couriers by accident while trying to trap proteins inside living cells. They are so small that they were at the limits of what could be visualised even by a super-resolution light microscope.