Coats of endosomal protein sorting: retromer and ESCRT.

Endosomes are hubs of endomembrane trafficking. They integrate vesicular traffic from different sources such as the plasma membrane or the Golgi apparatus and sort cargo to different destinations such as the vacuole, the plasma membrane or back to the Golgi apparatus. As endomembrane trafficking is largely via transport vesicles, endosomes employ different adaptor proteins and coats to accommodate their multiple functions. Retromer and ESCRT are coat/adapter combinations that are crucial for endosomal trafficking pathways. Retromer mediates recycling of sorting receptors back to the Golgi apparatus, ESCRT is needed for sorting of transmembrane cargo to the vacuole. While both are well-studied in yeast and animals, knowledge about their plant counterparts is still scarce. However, in recent years the mechanisms, targets and plant-specific functions of ESCRT and retromer have started to attract the interest of plant cell biologists also.