Role of the endocytic machinery in the sorting of lysosome-associated membrane proteins

The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, A...

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Bibliographic Details
Published in:Molecular biology of the cell 2005-09, Vol.16 (9), p.4231-4242
Main Authors: Janvier, Katy, Bonifacino, Juan S
Format: Article
Language:English
Subjects:
Adaptor Protein Complex 2 - biosynthesis
Adaptor Protein Complex 2 - genetics
Cell Membrane - genetics
Cell Membrane - metabolism
Clathrin - biosynthesis
Clathrin - genetics
Dynamins - biosynthesis
Dynamins - genetics
Endocytosis - genetics
Endocytosis - physiology
Fluorescent Antibody Technique
HeLa Cells
Humans
Lysosomal Membrane Proteins - biosynthesis
Lysosomal Membrane Proteins - genetics
Lysosomal Membrane Proteins - metabolism
Lysosomes - metabolism
Mutation
Protein Transport - genetics
Protein Transport - physiology
RNA Interference
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Summary:The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, AP-3, and AP-4, interact with such signals and are therefore candidates for mediating sorting of the Lamps to lysosomes. However, the role of these complexes and of the coat protein, clathrin, in sorting of the Lamps in vivo has either not been addressed or remains controversial. We have used RNA interference to show that AP-2 and clathrin-and to a lesser extent the other AP complexes-are required for efficient delivery of the Lamps to lysosomes. Because AP-2 is exclusively associated with plasma membrane clathrin coats, our observations imply that a significant population of Lamps traffic via the plasma membrane en route to lysosomes.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E05-03-0213