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Synaptobrevin
Synaptobrevins (''synaptobrevin isotypes 1-2'') are small integral membrane proteins of secretory vesicles with molecular weight of 18 kilodalton (kDa) that are part of the vesicle-associated membrane protein (VAMP) family. Synaptobrevin is one of the SNARE proteins involved in formation of the SNARE complexes. Structure Out of four α-helices of the core SNARE complex one is contributed by synaptobrevin, one by syntaxin, and two by SNAP-25 (in neurons). Function SNARE proteins are the key components of the molecular machinery that drives fusion of membranes in exocytosis. Their function however is subject to fine-tuning by various regulatory proteins collectively referred to as ''SNARE masters''. Classification In the Q/R nomenclature for organizing SNARE proteins, VAMP/synaptobrevin family members are classified as R-SNAREs, so named for the presence of an arginine at a specific location within the primary sequence of the protein (as opposed to the SNAREs of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R-SNAREs
SNARE proteins – "Soluble NSF attachment protein, SNAP REceptors" – are a large protein family consisting of at least 24 members in yeasts and more than 60 members in mammalian and plant cells. The primary role of SNARE proteins is to mediate the vesicle fusion, fusion of vesicles with the target Cell membrane, membrane; this notably mediates exocytosis, but can also mediate the fusion of vesicles with membrane-bound compartments (such as a lysosome). The best studied SNAREs are those that mediate the release of synaptic vesicles containing neurotransmitters in neurons. These neuronal SNAREs are the targets of the neurotoxins responsible for botulism and tetanus produced by certain bacteria. Types SNAREs can be divided into two categories: ''vesicle'' or ''v-SNAREs'', which are incorporated into the membranes of transport vesicles during budding, and ''target'' or ''t-SNAREs'', which are associated with nerve terminal membranes. Evidence suggests that t-SNAREs form s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q-SNARE
SNARE proteins – " SNAP REceptors" – are a large protein family consisting of at least 24 members in yeasts and more than 60 members in mammalian and plant cells. The primary role of SNARE proteins is to mediate the fusion of vesicles with the target membrane; this notably mediates exocytosis, but can also mediate the fusion of vesicles with membrane-bound compartments (such as a lysosome). The best studied SNAREs are those that mediate the release of synaptic vesicles containing neurotransmitters in neurons. These neuronal SNAREs are the targets of the neurotoxins responsible for botulism and tetanus produced by certain bacteria. Types SNAREs can be divided into two categories: ''vesicle'' or ''v-SNAREs'', which are incorporated into the membranes of transport vesicles during budding, and ''target'' or ''t-SNAREs'', which are associated with nerve terminal membranes. Evidence suggests that t-SNAREs form stable subcomplexes which serve as guides for v-SNARE, incorpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAMP2
Vesicle-associated membrane protein 2 (VAMP2) is a protein that in humans is encoded by the ''VAMP2'' gene. Function Synaptobrevins/VAMPs, syntaxins, and the 25-kD synaptosomal-associated protein SNAP25 are the main components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane. VAMP2 is a member of the vesicle-associated membrane protein (VAMP)/synaptobrevin family. VAMP2 is thought to participate in neurotransmitter release at a step between docking and fusion. Mice lacking functional synaptobrevin2/VAMP2 gene cannot survive after birth, and have a dramatically reduced synaptic transmission, around 10% of control. The protein forms a stable complex with syntaxin, synaptosomal-associated protein, 25 kD, and complexin. It also forms a distinct complex with synaptophysin. Clinical significance Heterozygous mutations in VAMP2 cause a neurodevelopmental disorder with hypotonia and autistic features (with or withou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SNAP-25
Synaptosomal-Associated Protein, 25kDa (SNAP-25) is a Target Soluble NSF (''N''-ethylmaleimide-sensitive factor) Attachment Protein Receptor ( t-SNARE) protein encoded by the ''SNAP25'' gene found on chromosome 20p12.2 in humans. SNAP-25 is a component of the ''trans''-SNARE complex, which accounts for membrane fusion specificity and directly executes fusion by forming a tight complex that brings the synaptic vesicle and plasma membranes together. Structure and function SNAP-25, a Q-SNARE protein, is anchored to the cytosolic face of membranes via palmitoyl side chains covalently bound to cysteine amino acid residues in the central linker domain of the molecule. This means that SNAP-25 does not contain a trans-membrane domain. SNAP-25 has been identified to contribute two α-helices to the SNARE complex, a four-α-helix domain complex. The SNARE complex participates in vesicle fusion, which involves the docking, priming and merging of a vesicle with the cell membran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetanospasmin
Tetanus toxin (TeNT) is an extremely potent neurotoxin produced by the vegetative cell of '' Clostridium tetani'' in anaerobic conditions, causing tetanus. It has no known function for clostridia in the soil environment where they are normally encountered. It is also called spasmogenic toxin, tentoxilysin, tetanospasmin, or tetanus neurotoxin. The LD50 of this toxin has been measured to be approximately 2.5–3 ng/kg, making it second only to the related botulinum toxin (LD50 2 ng/kg) as the deadliest toxin in the world. However, these tests are conducted solely on mice, which may react to the toxin differently from humans and other animals. ''C. tetani'' also produces the exotoxin tetanolysin, a hemolysin, that causes destruction of tissues. Distribution Tetanus toxin spreads through tissue spaces into the lymphatic and vascular systems. It enters the nervous system at the neuromuscular junctions and migrates through nerve trunks and into the central nervo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAMP1
Vesicle-associated membrane protein 1 (VAMP1) is a protein that in humans is encoded by the ''VAMP1'' gene. Function Synaptobrevins/VAMPs, syntaxins, and the 25-kD synaptosomal-associated protein SNAP25 are the main components of a protein complex involved in the docking and/or fusion of synaptic vesicles with the presynaptic membrane. VAMP1 is a member of the vesicle-associated membrane protein (VAMP)/synaptobrevin family. Multiple alternative splice variants that encode proteins with alternative carboxy ends have been described, but the full-length nature of some variants has not been defined. Clinical significance Homozygous mutations in VAMP1 have been identified in a series of children affected with a form of congenital myasthenic syndrome and similar presynaptic features in these patients and the knock-out VAMP1 mouse have been demonstrated. VAMP1 expression has been linked to higher survival rates for lung cancer Lung cancer, also known as lung carcinoma, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAMP5
Vesicle-associated membrane protein 5 (VAMP-5) is a synaptobrevin protein encoded in the human by the ''VAMP5'' gene. Function VAMPs (synaptobrevins) along with syntaxins and the 25-kD synaptosomal-associated protein are the main components of a protein complex involved in the docking and/or fusion of vesicles and cell membranes. The VAMP5 gene is a member of the vesicle-associated membrane protein (VAMP)/synaptobrevin family and the SNARE superfamily. This VAMP family member may participate in vesicle trafficking events that are associated with myogenesis Myogenesis is the formation of skeletal muscle, skeletal muscular tissue, particularly during embryonic development. Skeletal muscle#Skeletal muscle cells, Muscle fibers generally form through the fusion of precursor cell, precursor myoblasts in .... References External links * {{gene-2-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAMP7
Vesicle-associated membrane protein 7 (VAMP-7), is a protein that in humans is encoded by the ''VAMP7'' gene also known as the ''SYBL1'' gene. Function VAMP-7 is a transmembrane protein that is a member of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family. VAMP-7 localizes to late endosomes and lysosomes and is involved in the fusion of transport vesicles to their target membranes. Interactions VAMP-7 has been shown to interact with SNAP23 Synaptosomal-associated protein 23 is a protein that in humans is encoded by the ''SNAP23'' gene. Two alternative transcript variants encoding different protein isoforms have been described for this gene. Function Specificity of vesicular tran ... and AP3D1. References Further reading * * * * * * * * * * * * * * * * * External links * {{gene-X-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syntaxin
Syntaxins are a family of membrane integrated Q-SNARE proteins participating in exocytosis. Domains Syntaxins possess a single C-terminal transmembrane domain, a SNARE domain (known as H3), and an N-terminal regulatory domain (Habc). Syntaxin 17 may have two transmembrane domains. * The SNARE (H3) domain binds to both synaptobrevin and SNAP-25 forming the core SNARE complex. Formation of this stable SNARE core complex is believed to generate the free energy required to initiate fusion between the vesicle membrane and plasma membrane. * The N-terminal Habc domain is formed by 3 α-helices and when collapsed onto its own H3 helix forms an inactive "closed" syntaxin conformation. This closed conformation of syntaxin is believed to be stabilized by binding of Munc-18 (nSec1), although more recent data suggests that nSec1 may bind to other conformations of syntaxin, as well. The "open" syntaxin conformation is the conformation that is competent to form into SNARE core complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesicle-associated Membrane Protein
Vesicle associated membrane proteins (VAMPs) are a family of SNARE proteins with similar structure, and are mostly involved in vesicle fusion. * VAMP1 and VAMP2 proteins known as synaptobrevins are expressed in brain and are constituents of the synaptic vesicles, where they participate in neurotransmitter release. * VAMP3 (known as cellubrevin) is ubiquitously expressed and participates in regulated and constitutive exocytosis as a constituent of secretory granules and secretory vesicles. * VAMP5 and VAMP7 participate in constitutive exocytosis. ** VAMP5 is a constituent of secretory vesicles, myotubes and tubulovesicular structures. ** VAMP7 is found both in secretory granules and endosomes. * VAMP8 (known as endobrevin) participates in endocytosis and is found in early endosomes. VAMP8 also participates the regulated exocytosis in pancreatic acinar cells. *VAMP4 Vesicle-associated membrane protein 4 is a protein that in humans is encoded by the ''VAMP4'' gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exocytosis
Exocytosis is a term for the active transport process that transports large molecules from cell to the extracellular area. Hormones, proteins and neurotransmitters are examples of large molecules that can be transported out of the cell. Exocytosis is a crucial transport mechanism that enables polar molecules to flow through the cell membranes’ hydrophobic lipid bilayer. The transport process is essential to hormone secretion, immune response and neurotransmission. Both prokaryotes and eukaryotes undergo exocytosis. Prokaryotes secrete molecules and cellular waste through translocons that are localized to the cell membrane. In addition, they secrete molecules to other cells through specialized organs. Eukaryotes rely on multiple cellular processes to perform the exocytosis process. Eukaryotes have several organelles and a nucleus in the cytoplasm that are connected through multiple transport routes, that is formally known as the secretory pathway. This is a complex pathway with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
