Delivery of endocytosed membrane proteins to the lysosome

The delivery of proteins from the plasma membrane to the lysosome for degradation is essential for normal cellular function. There is now a good understanding of the protein complexes involved in sorting proteins at the plasma membrane and into the intralumenal vesicles of the multi-vesicular body. A combination of cell free content mixing assays and live-cell imaging has dissected out the final step in delivery of macromolecules to the lysosome from the multi-vesicular body and provided insights into the molecular mechanisms by which late endosomes and lysosomes exchange lumenal contents. The endocytic pathway has provided a platform with which to understand the autophagic and phagocytic pathways, but the fine details of how traffic through these pathways is regulated remain to be determined. (C) 2008 Elsevier B.V. All rights reserved.