Although it is known that proteins are delivered to and recycled from the plasma membrane (PM) via endosomes, the nature of the endosomal compartments and the pathways responsible for cargo and vesicle sorting and cellular signaling is poorly understood. More specifically, the molecular mechanisms that regulate protein trafficking to and from the plasma membrane, via interconnected endocytosis and recycling pathways, or towards the vacuole remain ill-defined due to the transient nature of endosomal compartments and their cargoes. We have pioneered a novel approach to the study of this cell-biological problem that involves identifying components and cargoes of this trafficking system using a combination of chemical genomics, proteomics and genetics. The significance of dissecting these processes is broad-based in that these sorting mechanisms can control the distribution of cellular receptors, transporters and other proteins that are critical for plant development or responses to pathogens and environment.