Retrograde trafficking and plasma membrane recycling pathways of the budding yeast Saccharomyces cerevisiae

The endosomal system functions as a network of protein and lipid sorting stations that receives molecules from endocytic and secretory pathways and directs them to the lysosome for degradation, or exports them from the endosome via retrograde trafficking or plasma membrane recycling pathways. Retrograde trafficking pathways describe endosome‐to‐Golgi transport while plasma membrane recycling pathways describe trafficking routes that return endocytosed molecules to the plasma membrane. These pathways are crucial for lysosome biogenesis, nutrient acquisition and homeostasis and for the physiological functions of many types of specialized cells. Retrograde and recycling sorting machineries of eukaryotic cells were identified chiefly through genetic screens using the budding yeast Saccharomyces cerevisiae system and discovered to be highly conserved in structures and functions. In this review, we discuss advances regarding retrograde trafficking and recycling pathways, including new discoveries that challenge existing ideas about the organization of the endosomal system, as well as how these pathways intersect with cellular homeostasis pathways. Retrograde trafficking and plasma membrane recycling pathways originating from the endosome serve many physiological functions, including facilitating the reuse of sorting receptors in organelle biogenesis pathways and controlling plasma membrane composition. Genetic studies using Saccharomyces cerevisiae first identified machineries involved in retrograde and recycling sorting pathways, many of which are highly conserved. Recent advances in yeast give insight into how these pathways intersect with cellular homeostasis pathways and challenge existing ideas about the organization of the endosomal system.