Retromer at the vacuole

Membrane proteins that are involved in vesicular transport are recycled through carefully controlled processes that are coordinated with the retrograde transport of membranes from the target organelle. One of the factors that mediates recycling of protein-sorting receptors from endosomal membranes back to the Golgi is the retromer complex. Interestingly, the retromer subunit Vps35 has also been found at the vacuole, but retromer function at this organelle has not been investigated in detail. On page 645, Christian Ungermann and colleagues now develop an assay that allows them to follow the recycling of membrane protein from the vacuole by exploring the mislocalisation of the retromer cargo protein Vps10. Using this approach, the authors first show that retromer can recycle Vps10 from vacuoles, similar to its function in endosomal recycling, and that this also requires the Rab Ypt7 and the dynamin-like Vps1. Here, Ypt7 is involved in the initiation of recycling as it remains at the vacuole, whereas Vps10 and some of the retromer subunits subsequently reappear at endosomes and the Golgi. Furthermore, using vps1 mutants, the authors show that Vps1 is involved in the fission of retromer-containing tubules that form at the surface of the vacuole, similar to its suggested function in endosomal sorting. Taken together, the data presented here point to a versatile role of retromer in receptor recycling from different organelles, including the vacuole.