ABSTRACT
Protein sorting within the endosomal system can yield several outcomes. One outcome is sorting into the intralumenal vesicles of a multivesicular body (MVB). MVB formation is required for a number of important cellular functions. It has been appreciated for some time that some cell surface receptors are sorted into MVBs en route to the lysosome/ vacuole for degradation. Proper spatial and temporal degradation of signaling receptors is im portant in the context of growth control, and dysfunction of these processes can lead to devel opmental defects or even tumorigenesis. More recently, it has come to be appreciated that the Mvb sorting pathway is required for certain non-degradative functions as well, including proper immune response and the budding of viral particles. Advances in our understanding of the
acting signals for selection by this pathway and the trans-acting components that play a role in recognition of cargoes are the focus of this chapter.
