Protein and lipid requirements for endocytosis

Genetic and biochemical studies in yeast and animal cells have led to the i dentification of many components required for endocytosis. In this review w e summarize our understanding of the endocytic machinery with an emphasis o n the proteins regulating the internalization step of endocytosis and endos ome fusion. Even though the overall endocytic machinery appears to be conse rved between yeast and animals, clear differences exist. We also discuss th e roles of phosphoinositides, sterols, and sphingolipid precursors in endoc ytosis, because in addition to proteins, these lipids have emerged as impor tant determinants in the spatial and most likely temporal specificity of en docytic membrane trafficking events.