Endothelial caveolae have the molecular transport machinery for vesicle budding, docking, and fusion including VAMP, NSF, SNAP, annexins, and GTPases.
Transport by discrete vesicular carriers is well established at least in part because of recent discoveries identifying key protein mediators of vesicle formation, docking, and fusion. A general mechanism sensitive to N-ethylmaleimide (NEM) is required for the transport of a divergent group of vesicular carriers in all eukaryotes. Many endothelia have an abundant population of non-coated plasmalemmal vesicles or caveolae, which have been reported with considerable controversy to function in transport. We recently have shown that like other vesicular transport systems, caveolae-mediated endocytosis and transcytosis are inhibited by NEM (Schnitzer, J. E., Allard, J., and Oh, P. (1995) Am. J. Physiol. 268, H48-H55). Here, we continue this work by utilizing our recently developed method for purifying endothelial caveolae from rat lung tissue (Schnitzer, J. E., Oh, P., Jacobson, B. S., and Dvorak, A. M. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 1759-1763) to show that these caveolae contain key proteins known to mediate different aspects of vesicle formation, docking, and/or fusion including the vSNARE VAMP-2, monomeric and trimeric GTPases, annexins II and VI, and the NEM-sensitive fusion factor NSF along with its attachment protein SNAP. Like neuronal VAMPs, this endothelial VAMP is sensitive to cleavage by botulinum B and tetanus neurotoxins. Caveolae in endothelium are indeed like other carrier vesicles and contain similar NEM-sensitive molecular machinery for transport.
Schnitzer
J E
JE
Department of Pathology, Harvard Medical School, Beth Israel Hospital, Boston, Massachusetts 02215, USA.
Liu
J
J
Oh
P
P
D000818:Animals; D017302:Annexins / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002459:Cell Fusion; D004727:Endothelium / Q000378:metabolism / Q000648:ultrastructure*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D052066:N-Ethylmaleimide-Sensitive Proteins; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000378:metabolism*; D050683:R-SNARE Proteins; D051381:Rats; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D014118:Toxins, Biological / Q000494:pharmacology; D033921:Vesicular Transport Proteins
D017302:Annexins; D002352:Carrier Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050683:R-SNARE Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D014118:Toxins, Biological; D033921:Vesicular Transport Proteins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins; C498737:Nsf protein, rat