Endobrevin, a novel synaptobrevin/VAMP-like protein preferentially associated with the early endosome.
Synaptobrevins/vesicle-associated membrane proteins (VAMPs) together with syntaxins and a synaptosome-associated protein of 25 kDa (SNAP-25) are the main components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane. We report here the molecular, biochemical, and cell biological characterization of a novel member of the synaptobrevin/VAMP family. The amino acid sequence of endobrevin has 32, 33, and 31% identity to those of synaptobrevin/VAMP-1, synaptobrevin/VAMP-2, and cellubrevin, respectively. Membrane fractionation studies demonstrate that endobrevin is enriched in membrane fractions that are also enriched in the asialoglycoprotein receptor. Indirect immunofluorescence microscopy establishes that endobrevin is primarily associated with the perinuclear vesicular structures of the early endocytic compartment. The preferential association of endobrevin with the early endosome was further established by electron microscopy (EM) immunogold labeling. In vitro binding assays show that endobrevin interacts with immobilized recombinant alpha-SNAP fused to glutathione S-transferase (GST). Our results highlight the general importance of members of the synaptobrevin/VAMP protein family in membrane traffic and provide new avenues for future functional and mechanistic studies of this protein as well as the endocytotic pathway.
Wong
S H
SH
Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Singapore 117609, Singapore.
Zhang
T
T
Xu
Y
Y
Subramaniam
V N
VN
Griffiths
G
G
Hong
W
W
D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D037263:Asialoglycoprotein Receptor; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane; D002522:Chlorocebus aethiops; D018076:DNA, Complementary; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D050683:R-SNARE Proteins; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D014407:Tumor Cells, Cultured; D014709:Vero Cells; D033921:Vesicular Transport Proteins; D000077191:Wortmannin
D000730:Androstadienes; D037263:Asialoglycoprotein Receptor; D002352:Carrier Proteins; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D050683:R-SNARE Proteins; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; C112938:VAMP8 protein, human; C491831:Vamp8 protein, mouse; C491830:Vamp8 protein, rat; D033921:Vesicular Transport Proteins; D000077191:Wortmannin