VAMP-7 mediates vesicular transport from endosomes to lysosomes.
A more complete picture of the molecules that are critical for the organization of membrane compartments is beginning to emerge through the characterization of proteins in the vesicle-associated membrane protein (also called synaptobrevin) family of membrane trafficking proteins. To better understand the mechanisms of membrane trafficking within the endocytic pathway, we generated a series of monoclonal and polyclonal antibodies against the cytoplasmic domain of vesicle-associated membrane protein 7 (VAMP-7). The antibodies recognize a 25-kD membrane-associated protein in multiple tissues and cell lines. Immunohistochemical analysis reveals colocalization with a marker of late endosomes and lysosomes, lysosome-associated membrane protein 1 (LAMP-1), but not with other membrane markers, including p115 and transferrin receptor. Treatment with nocodozole or brefeldin A does not disrupt the colocalization of VAMP-7 and LAMP-1. Immunoelectron microscopy analysis shows that VAMP-7 is most concentrated in the trans-Golgi network region of the cell as well as late endosomes and transport vesicles that do not contain the mannose-6 phosphate receptor. In streptolysin- O-permeabilized cells, antibodies against VAMP-7 inhibit the breakdown of epidermal growth factor but not the recycling of transferrin. These data are consistent with a role for VAMP-7 in the vesicular transport of proteins from the early endosome to the lysosome.
Advani
R J
RJ
Medical School, University of Utrecht, Institute for Biomembranes, 3584CX Utrecht, The Netherlands.
Yang
B
B
Prekeris
R
R
Lee
K C
KC
Klumperman
J
J
Scheller
R H
RH
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D002463:Cell Membrane Permeability; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D015870:Gene Expression; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D052118:Lysosomal-Associated Membrane Protein 1; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D016253:Microscopy, Immunoelectron; D015739:Nocodazole / Q000494:pharmacology; D050683:R-SNARE Proteins; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D050600:SNARE Proteins; D014168:Transferrin / Q000378:metabolism; D033921:Vesicular Transport Proteins
D015703:Antigens, CD; C489116:LAMP1 protein, human; C052255:Lamp1 protein, mouse; C489117:Lamp1 protein, rat; D052118:Lysosomal-Associated Membrane Protein 1; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; C496927:Sybl1 protein, mouse; D014168:Transferrin; C121241:VAMP7 protein, human; C496926:Vamp7 protein, rat; D033921:Vesicular Transport Proteins; D020126:Brefeldin A; D004815:Epidermal Growth Factor; D015739:Nocodazole