Synaptobrevin

VAPB Vesicle-associated membrane protein (VAMP)-associated protein B (aka VAPB) is a type IV transmembrane protein and belongs to the VAP family of proteins. VAPB may have a role in vesicle trafficking. VAPB is found in plasma and intracellular vesicle membranes as a homodimer and heterodimer with VAPA, and interacts with VAMP1 and VAMP2. VAPB defects are the basis for the amyotrophic lateral sclerosis type 8 and spinal muscular atrophy autosomal dominant Finkel type.

VAPA is involved in vesicle traficking. VAPA is a type IV membrane protein. It is localized in the plasma membrane and intracellular vesicles. VAPA is related with the cytoskeleton. VAPA functions membrane fusion, protein complex assembly and cell motility. VAPA is an essential regulator both of the subcellular localization of protrudin and of its ability to stimulate neurite outgrowth.

VAMP8 also called endobrevin, is the main component of a SNARE complex involved in the docking and fusion of synaptic vesicles with the presynaptic membrane. VAMP8 protein is involved in the regulatation of enzyme secretion in pancreatic acinar cells and plays a part in the abscission of the midbody during cell division, which leads to completely separate daughter cells. VAMP8 is essential for dense-granule secretion in platelets. VAMP8 is related with the perinuclear vesicular structures of the early endocytic compartment. VAMP8 interacts particularly with the soluble NSF-attachment protein (alpha-SNAP), through an VAMP8-containing SNARE complex.

Vesicle-Associated Membrane Protein 7 (VAMP7) is a member of the synaptobrevin family. VAMP7 is a transmembrane protein, which is a member of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family. VAMP7 is involved in the targeting and/or fusion of transport vesicles to their target membrane during transport of proteins from the early endosome to the lysosome. VAMP7 localizes to late endosomes and lysosomes and is involved in the fusion of transport vesicles to their target membranes. VAMP7 is essential for heterotypic fusion of late endosomes with lysosomes and homotypic lysosomal fusion. It is also necessary for calcium regulated lysosomal exocytosis. In addition, VAMP7 is involved in the export of chylomicrons from the endoplasmic reticulum to the cis Golgi. Furthermore, VAMP7 is needed for exocytosis of mediators during eosinophil and neutrophil degranulation, and target cell killing by natural killer cells.

VAMP5 is part of the vesicle-associated membrane protein (VAMP)/synaptobrevin family and the SNARE superfamily. VAMP5 is involved is vesicle trafficking events that are associated with myogenesis.

VAMP4 belongs to the synaptobrevin family who are involved in docking and/or fusion of vesicles with cell membrane. VAMP4 is enriched in the trans-Golgi network and may be a factor in the trans-Golgi network-to-endosome transport. VAMP4 is involved in the pathway which functions to eliminate an inhibitor (most likely synaptotagmin-4) of calcium-triggered exocytosis during the maturation of secretory granules. Synaptobrevins, syntaxins, and SNAP25 are the chief components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane.

VAMP3 is present in recycling endosomes and endosome-derived vesicles. VAMP3 has been implicated in recycling of transferrin receptors to the plasma membrane, secretion of alpha-granules in platelets, recycling of T-cell receptors to the immunological synapses, and membrane trafficking during cell migration. VAMP-3 is present in human platelets and necessary for granule secretion. Synaptobrevins are the main components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane. VAMP3 high homology to other VAMPs in its broad tissue distribution and subcellular localization is shown to be the human equivalent of the rodent cellubrevin. In platelets the protein resides on a compartment that is not mobilized to the plasma membrane on calcium or thrombin stimulation.

Synaptobrevin 2 which is an 18 kDa integral membrane protein localized to the cytoplasmic surface of synaptic vesicle, consists of a proline-rich N-terminal region, a highly conserved hydrophilic domain, followed by a transmembrane anchor and a C-terminal. Synaptobrevin 2 is predominantly expressed in Langerhans islets and glomerular cells. The N-terminal domain of the protein (residues 1-89) forms a specific SNARE complex with the target membrane-associated t- or Q-SNAREs syntaxin 1 and SNAP-25.

Synaptobrevin-2 or VAMP2 is a protein that has a proline-rich N-terminal part, highly conserved hydrophilic domain, a transmembrane anchor and a C-terminal.VAMP2 found in the transmembrane region of the cell, in the cytoplasmic surface of the synaptic vesicle. The protein is mainly found in the Langerhans islets in the pancreas and glomerular cells in the kidney. A SNARE complex is created within the protein’s N-terminal domain and the target membrane-associated T.

Synaptobrevin 2 which is an 18 kDa integral membrane protein localized to the cytoplasmic surface of synaptic vesicle, consists of a proline-rich N-terminal region, a highly conserved hydrophilic domain, followed by a transmembrane anchor and a C-terminal. Synaptobrevin 2 is predominantly expressed in Langerhans islets and glomerular cells. The N-terminal domain of the protein (residues 1-89) forms a specific SNARE complex with the target membrane-associated t- or Q-SNAREs syntaxin 1 and SNAP-25.

Synaptobrevin 1(Vehicle-associated membrane, VAMP1) is one of the key proteins in the SNARE complex which is involved in regulated exocytosis. Synaptobrevin1 binds to t-SNAREs, syntaxin (STX) and SNAP25, after the fusion of synaptic vesicles to plasma membrane.