This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Cells constantly recycle proteins and other cellular components. But how do they ensure that the right cargo ends up in the right recycling vesicle—one of the cell's transport carriers?
A team at the University of Basel has identified a molecular switch that controls this process. The small protein ARF-1 ensures that recyclable cargo is efficiently loaded into transport vesicles and returned to the cell's surface. Cells are masters of recycling.
Proteins and other components taken up from the cell surface are first delivered to endosomes, the cell's sorting stations. There, their fate is decided: Some are sent for degradation, while others are recycled and returned to the cell membrane. In earlier work, the team led by professor Anne Spang at the Biozentrum, University of Basel, discovered the protein machinery FERARI, which plays a central role in this process.
Recycling vesicles dock onto sorting endosomes and partially fuse with them. The vesicle remains intact and can detach again. This process is known as "kiss-and-run." The researchers also showed that material is exchanged in both directions during this brief contact.
What remained unclear, however, was how the cell decides which proteins actually make their way into the recycling vesicle. The researchers have now identified a mechanism that controls this sorting process. At its center is ARF-1, a small regulatory protein that switches between an active and an inactive state.
The results of the study have been published in the Journal of Cell Biology. "We were able to show that ARF-1 acts like a molecular switch during vesicle loading," explains first author Dr. "Crucially, ARF-1 must constantly cycle between its active and inactive states.
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