The gene is a member of the syntaxin family. The encoded protein is targeted to the apical membrane of epithelial cells where it forms clusters and is important in establishing and maintaining polarity necessary for protein trafficking involving vesicle fusion and exocytosis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, May 2010] ...
How is Target-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor abbreviated? t-SNARE stands for Target-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor. t-SNARE is defined as Target-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor rarely.
Although many unique SNAREs with specific locations have been identified, we are only beginning to understand how these proteins regulate the specificity of particular vesicle-mediated transport pathways. The hemopoietic cell lineage, with the rather peculiar feature of secretory lysosomes, may use specialized mechanisms for sorting and secretion, which differ from those found in conventional secretory cells (7). Taking RBL-2H3 cells as a model for mast cells, we show that several isoforms of the three SNARE protein families are expressed and that they form different sets of complexes in intact cells. We provide evidence for a functional role of syntaxin 4 in FcεRI-stimulated secretion and for the localization of its binding partner, the v-SNARE VAMP8, on secretory granules.. Identification of t-SNARE proteins SNAP23, syntaxin 3, and syntaxin 4 as well as the v-SNARE VAMP2 corroborates previous observations in rat peritoneal mast cells (42). However, in adherent RBL-2H3 cells, SNAP23 is ...
Qa-SNARE Proteins: A subfamily of Q-SNARE PROTEINS which occupy the same position as syntaxin 1A in the SNARE complex and which also are most similar to syntaxin 1A in their AMINO ACID SEQUENCE. This subfamily is also known as the syntaxins, although a few so called syntaxins are Qc-SNARES.
In support of this hypothesis, defects in SNARE complex assembly and traffic through the endosomal system due to the loss of Vps45p (Vps is vacuolar protein sorting) are bypassed by a version of the yeast endocytic Sx, Tlg2p, lacking its Habc domain [19]. These results support a model whereby Vps45p activates Tlg2p for entry into functional SNARE complexes by facilitating its switch from a closed to an open conformation. The version lacking the Habc domain is unable to adopt the closed conformation and therefore does not require activation (opening) by Vps45p. Although these functional studies indicate that, like the plasma membrane Sxs described above, Tlg2p adopts a closed conformation that is incompatible with SNARE complex formation, NMR spectroscopy studies have been used to argue that this endosomal Sx does not adopt a closed conformation [20]. However, the bacterially produced version of Tlg2p used in these studies lacked almost half of the SNARE motif. Through analogy with the closed ...
Fig. 2. Stages involved in vesicle-membrane fusion and key proteins involved. The proteins in the central schematic are color coded as follows: synaptobrevin, dark blue; synaptophysin, light blue; syntaxin, red; nSec1, brown; SNAP-25, green; synaptotagmin, yellow; Rab3A, dark red circle; rabphilin-3A, olive green; Ca2+ channel, magenta; NSF, pink circle; α-SNAP, sky blue. Surrounding the schematic are crystal structures of the SNARE complex (blue: synaptobrevin; red: syntaxin; green: SNAP-25) [29], the N-terminal domain of syntaxin, which is shown as a separate structure (the structure of the linker between the syntaxin N-terminal domain and the core SNARE complex is unknown) [30], the nSec1-syntaxin complex (red: syntaxin; brown: nSec1) [38••], α-SNAP (Sec17 in yeast) [110••], NSF-N[106••.] and [107••.], NSF-D2 [103.] and [104.], the complex between the small G protein Rab3A and the effector binding domain of rabphilin-3A (red: Rab3A; brown: rabphilin-3A) [92••], Rab GDI ...
The co-expression of SERT and syntaxin 1A led to a significant reduction in the Vmax, but not the Km, for [3H]5-HT uptake. Similarly, syntaxin 1A co-expression greatly reduced parachloroamphetamine-induced SERT-dependent efflux. Neither the pharmacological inhibition of CaMKII, nor the mutation of a CaMKII-binding motif in the N-terminal tail of SERT had any effect on the down-regulation of SERT activity by syntaxin 1A in neuronal cell lines. In contrast to SERT, the co-expression of syntaxin 1A and DAT had no effect on [3H]MPP+ uptake via DAT. Moreover, D-amphetamine-induced efflux via DAT was increased by the co-expression of syntaxin 1A. ...
Plasma membrane t-SNARE that mediates docking of transport vesicles. Necessary for the translocation of SLC2A4 from intracellular vesicles to the plasma membrane. May also play a role in docking of synaptic vesicles at presynaptic active zones (By similarity).
From NCBI Gene:. The gene is a member of the syntaxin family. The encoded protein is targeted to the apical membrane of epithelial cells where it forms clusters and is important in establishing and maintaining polarity necessary for protein trafficking involving vesicle fusion and exocytosis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, May 2010]. From UniProt: ...
There are no specific protocols for Recombinant Human Syntaxin 1a protein (ab86442). Please download our general protocols booklet
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cis-SNARE complex (SNARE) -- are a large protein superfamily consisting of more than 60 members in yeast and mammalian cells. fact lexicon with terms going straight to the point. Facts are sorted by community importance and you can build your personalized lexicon
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Mso1p-Sec4p colocalization is depended on Sec2p and independent of a functional SNARE complex. (A) wt, (B) sso2-1 Δsso1, and (C) sec2-41 cells coexpressing
Syntaxin 1A. (Aliases: Syt1A,SYX1A,CG5448,CG10716,synt,anon-EST:Gibbs4,Syx1,Dm Syx1,syx-1,l(3)06737,dSyx1,CT30033,Dmel\CG31136,syx-1A,Syx,Syx-1A,syt-1A,syx1A,syx,syx1,SyxA,DmSyx1A,Syx1a,CG18615,anon-WO02059370.54,CG31136) ...
When nerve cells communicate, vesicles from one neuron fuse with the presynaptic membrane releasing chemicals that signal to the next. Similarly, when insulin binds its receptor on adipocytes or muscle, glucose transporter-4 vesicles fuse with the cell membrane, allowing glucose to be imported. These essential processes require the interaction of SNARE proteins on vesicle and cell membranes, as well as the enigmatic protein Munc18 that binds the SNARE protein Syntaxin. Here, we show that in solution the neuronal protein Syntaxin1a interacts with Munc18-1 whether or not the Syntaxin1a N-peptide is present. Conversely, the adipocyte protein Syntaxin4 does not bind its partner Munc18c unless the N-peptide is present. Solution-scattering data for the Munc18-1:Syntaxin1a complex in the absence of the N-peptide indicates that this complex adopts the inhibitory closed binding mode, exemplified by a crystal structure of the complex. However, when the N-peptide is present, the solution-scattering data indicate
Syntaxin-binding protein 3 is a protein that in humans is encoded by the STXBP3 gene. Syntaxin binding protein 3 has been shown to interact with STX2 and STX4. GRCh38: Ensembl release 89: ENSG00000116266 - Ensembl, May 2017 GRCm38: Ensembl release 89: ENSMUSG00000027882 - Ensembl, May 2017 "Human PubMed Reference:". "Mouse PubMed Reference:". Reed GL, Houng AK, Fitzgerald ML (May 1999). "Human platelets contain SNARE proteins and a Sec1p homologue that interacts with syntaxin 4 and is phosphorylated after thrombin activation: implications for platelet secretion". Blood. 93 (8): 2617-26. PMID 10194441. "Entrez Gene: STXBP3 syntaxin binding protein 3". Schraw, Todd D; Lemons Paula P; Dean William L; Whiteheart Sidney W (Aug 2003). "A role for Sec1/Munc18 proteins in platelet exocytosis". Biochem. J. England. 374 (Pt 1): 207-17. doi:10.1042/BJ20030610. ISSN 0264-6021. PMC 1223584 . PMID 12773094. Widberg, Charlotte H; Bryant Nia J; Girotti Milena; Rea Shane; James David E (Sep 2003). "Tomosyn ...
In eukaryotic cells, membrane-bound vesicles carry cargo between intracellular compartments, to and from the cell surface, and to the extracellular environment. Many conserved families of proteins are required for properly localized vesicle fusion, including the multi-subunit tethering complexes and the SNARE complexes. These protein complexes work together to promote proper vesicle fusion in other trafficking pathways. Contrary to these other pathways, our lab previously suggested that the exocyst subunit Sec6, a component of the exocytosis-specific tethering complex, inhibited Sec9:Sso1 SNARE complex assembly due to interactions in vitro with the SNARE protein Sec9 (Sivaram et al., 2005). My goal for this project was to test the hypothesis that Sec6 inhibited SNARE complex assembly in vivo. I therefore chose to generate Sec6:Sec9 loss-of-binding mutants, and study their effect both in vitro and in vivo. I identified a patch of residues on Sec9 that, when mutated, are sufficient to disrupt the novel
It is a widely accepted notion that trans-SNARE complexes start to assemble by pairing v-SNAREs and target SNAREs from their N-terminal ends. Complex formation then progresses in a "zipper"-like fashion toward the C-terminal TMD. Since the C-terminal portion of the SNARE motif of SybII has a lower propensity to form an α-helix, folding of the trans-SNARE complex may transiently stop or slow down (Ellena et al., 2009). Such partially assembled SNARE complexes may provide the stage for priming of secretory vesicles that await the Ca2+ stimulus and then rapidly fuse in response to the triggering signal (Sørensen et al., 2006). Intriguingly, our results show that a doublet of Trp residues located at the very C-terminal end of the cytoplasmic domain of SybII facilitates exocytosis competence and priming stability of secretory vesicles, while these processes have previously been assigned to N-terminal portions of the SNARE proteins (Borisovska et al., 2005; Sørensen et al., 2006; Wadel et al., ...
Shop Probable Golgi SNAP receptor complex ELISA Kit, Recombinant Protein and Probable Golgi SNAP receptor complex Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
The SNARE hypothesis states that the folding and assembly of four-helix SNARE complex bundles drives intracellular membrane fusion, including fusion in exocytos...
An intravascular snare device for use in capturing debris found in blood vessels. The snare device is fabricated from a tube and includes longitudinally and circumferentially extending members. The snare device specifically embodies structure that provides enhanced radial opening and angular resistance to collapse.
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Vesicle (v) and target (t) SNAREs reside on opposing membranes. (A) In response to stimulus the vesicle translocates near to the target membrane and the four SN
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مقدمه: اکسی‌آنیون‌های سلنیوم محلول به‌ویژه سلنیت در منابع آب و خاک وضعیت نگران‌کننده‌ای برای سلامت افراد و محیط زیست ایجاد کرده است. در این بررسی غربالگری باکتری‌های مولد اسیدلاکتیک مقاوم به سلنیت و توانایی آن‌ها به‌عنوان زیست کاتالیزگر ایمن در زیست‌پالایی سلنیت ارزیابی شد. مواد و روش‌ها: تعیین حداقل غلظت ممانعت‌کنندگی از رشد (MIC) و حداقل غلظت کشندگی (MBC) جدایه‌های باکتری نسبت به سلنیت با روش رقت در آگار تعیین شد. ارزیابی اثر مهارکنندگی سلنیت بر جدایه‌های باکتری با روش انتشار در چاهک انجام شد. از روش کدورت‌سنجی برای بررسی سنتتیک رشد استفاده شد.
The soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) protein syntaxin‐1 adopts a closed conformation when bound to Munc18‐1, preventing binding to synaptobrevin‐2 and SNAP‐25 to form the ternary SNARE complex. Although it is known that the MUN domain of Munc13‐1 catalyzes the transition from the Munc18‐1/syntaxin‐1 complex to the SNARE complex, the molecular mechanism is unclear. Here, we identified two conserved residues (R151, I155) in the syntaxin‐1 linker region as key sites for the MUN domain interaction. This interaction is essential for SNARE complex formation in vitro and synaptic vesicle priming in neuronal cultures. Moreover, this interaction is important for a tripartite Munc18‐1/syntaxin‐1/MUN complex, in which syntaxin‐1 still adopts a closed conformation tightly bound to Munc18‐1, whereas the syntaxin‐1 linker region changes its conformation, similar to that of the LE mutant of syntaxin‐1 when bound to Munc18‐1. We ...
The soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) protein syntaxin‐1 adopts a closed conformation when bound to Munc18‐1, preventing binding to synaptobrevin‐2 and SNAP‐25 to form the ternary SNARE complex. Although it is known that the MUN domain of Munc13‐1 catalyzes the transition from the Munc18‐1/syntaxin‐1 complex to the SNARE complex, the molecular mechanism is unclear. Here, we identified two conserved residues (R151, I155) in the syntaxin‐1 linker region as key sites for the MUN domain interaction. This interaction is essential for SNARE complex formation in vitro and synaptic vesicle priming in neuronal cultures. Moreover, this interaction is important for a tripartite Munc18‐1/syntaxin‐1/MUN complex, in which syntaxin‐1 still adopts a closed conformation tightly bound to Munc18‐1, whereas the syntaxin‐1 linker region changes its conformation, similar to that of the LE mutant of syntaxin‐1 when bound to Munc18‐1. We ...
Cytotoxic T lymphocytes (CTLs) kill target cells by secretion of cytotoxic components such as perforin and granzymes which are contained in lytic granules. Fusion of lytic granules occurs at the contact zone between the target cell and the CTL, the immunological synapse (IS). T cell receptor (TCR) enrichment at the IS is one of the key early events of IS formation. Soluble NSF attachment receptor (SNARE) proteins are required for all fusion events in cells, but the individual SNARE proteins that are important for CTL function are not yet known. We identified syntaxin 7 in CTLs by reverse transcriptase PCR and immunocytochemistry. We found that syntaxin 7 is localised to the IS with a similar distribution to the lytic granule marker - perforin. We then blocked the function of syntaxin 7 by deleting its transmembrane domain and observed a complete loss of TCR accumulation at the IS, indicating that no IS is formed. These results imply that syntaxin 7 is required for IS formation in CTLs. Further ...
Assembly of the SNARE proteins syntaxin1, SNAP25, and synaptobrevin into a SNARE complex is essential for exocytosis in neurons. For efficient assembly, SNAREs interact with additional proteins but neither the nature of the intermediates nor the sequence of protein assembly is known. Here, we have characterized a ternary complex between syntaxin1, SNAP25, and the SM protein Munc18‐1 as a possible acceptor complex for the R‐SNARE synaptobrevin. The ternary complex binds synaptobrevin with fast kinetics, resulting in the rapid formation of a fully zippered SNARE complex to which Munc18‐1 remains tethered by the N‐terminal domain of syntaxin1. Intriguingly, only one of the synaptobrevin truncation mutants (Syb1‐65) was able to bind to the syntaxin1:SNAP25:Munc18‐1 complex, suggesting either a cooperative zippering mechanism that proceeds bidirectionally or the progressive R‐SNARE binding via an SM template. Moreover, the complex is resistant to disassembly by NSF. Based on these ...
The botulinum toxin as a therapeutic agent: molecular and pharmacological insights Roshan Kukreja,1 Bal Ram Singh2 1Department of Chemistry and Biochemistry, University of Massachusetts, 2Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA, USA Abstract: Botulinum neurotoxins (BoNTs), the most potent toxins known to mankind, are metalloproteases that act on nerve–muscle junctions to block exocytosis through a very specific and exclusive endopeptidase activity against soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins of presynaptic vesicle fusion machinery. This very ability of the toxins to produce flaccid muscle paralysis through chemical denervation has been put to good use, and these potentially lethal toxins have been licensed to treat an ever expanding list of medical disorders and more popularly in the field of esthetic medicine. In most cases, therapeutic BoNT preparations are high-molecular-weight protein complexes consisting of
In this study we show using in vitro and in vivo approaches that in neuroendocrine cells munc18-1 has two modes of binding to syntaxin 1a. I show that munc 18-1 plays a vital role in binding to a closed-form of syntaxin 1a, keeping syntaxin 1a inactive and permitting its trafficking to the plasma membrane. Munc18-1 is also able to bind to an active open form of syntaxin 1a, allowing it to bind to other SNAREs. I demonstrate that in the absence of munc 18-1, syntaxin 1a and SNAP-25 can readily interact in the Golgi complex, forming reactive SNARE complexes that fail to traffic to plasma membrane. The exocytotic SNARE proteins are highly promiscuous in their interactions with other SNAREs, and thus it is essential to traffic the exocytotic SNARE proteins through intracellular compartments while avoiding ectopic interactions between non-cognate SNARE proteins. Munc 18-1 has a vital regulatory role in preventing the formation of the binary complex between syntaxin 1a and SNAP-25 before the proteins ...
Members of the Munc 18/Sec1 family, such as Sly 1p, play essential roles in membrane trafficking. The proteins bind to t-SNAREs (components of the SNARE complexes that drive membrane fusion); however, their exact role is far from clear, since some experiments suggest that they can inhibit membrane fusion. Koji Yoda and co-workers now demonstrate that Sly 1p directly stimulates SNARE assembly (see p. 3683). They show that the interaction between Sly 1p and the t-SNARE Sed5p is significantly reduced in a temperature-sensitive Sly1ts mutant and that Sly1pts protein has a lower affinity for Sed5p than does its wild-type counterpart. Most significant, however, is the authors use of a novel in vitro assay for SNARE complex assembly in Sly1ts mutant lysates, in which they show that purified Sly1 protein stimulates the formation of trans-SNARE complexes involving Sed5p and its partner the v-SNARE Bet1p. Since Sly1p-Sed5p binding is unaffected by SNARE complex formation, Yoda and co-workers propose that ...
Timmers KI, Clark AE, Omatsu-Kanbe M, Whiteheart SW, Bennett MK, Holman GD and Cushman SW. Experimental Diabetes, Metabolism and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.. The vesicle-associated membrane proteins [VAMPs; vesicle SNAP receptors (v-SNAREs)] present on GLUT4-enriched vesicles prepared from rat adipose cells [Cain, Trimble and Lienhard (1992) J. Biol. Chem. 267, 11681-11684] have been identified as synaptobrevin 2 (VAMP 2) and cellubrevin (VAMP 3) by using isoform-specific antisera. Additional antisera identify syntaxins 2 and 4 as the predominant target membrane SNAP receptors (t-SNAREs) in the plasma membranes (PM), with syntaxin 3 at one-twentieth the level. Syntaxins 2 and 4 are enriched 5-10-fold in PM compared with low-density microsomes (LDM). Insulin treatment results in an 11-fold increase in immunodetectable GLUT4 in PM and smaller (approx. 2-fold) increases in VAMP 2 and ...
The KOMP Repository is located at the University of California Davis and Childrens Hospital Oakland Research Institute. Question? Comments? For Mice, Cells, and germplasm please contact us at [email protected], US 1-888-KOMP-MICE or International +1-530-752-KOMP, or for vectors [email protected] or +1-510-450-7917 ...
Because AQP3 but not AQP5 was delivered to cell-cell contacts, we directly tested whether a targeting patch specific for basolateral vesicles is assembled upon E-cadherin-mediated cell-cell adhesion. Our data indicate that microtubules, the exocyst, and t-SNAREs are essential components of this lateral targeting patch. We showed that the exocyst and the t-SNARE syntaxin 4 colocalized with E-cadherin at early cell-cell contacts, and it has been shown by others that microtubule plus ends extend radially into cell-cell contacts (Stehbens et al., 2006; Shaw et al., 2007). Functional disruption of any one of these components did not interfere with the establishment of cell-cell adhesion or the localization of other components to cell-cell contact. Because there is a large amount of E-cadherin on the cell surface before cell adhesion (Adams et al. 1998), it is therefore likely that initial cell-cell adhesion does not require the delivery of E-cadherin from intracellular compartments. However, ...
The formation and dissolution of SNARE protein complexes is essential for Ca(2+)-triggered fusion of neurotransmitter-filled vesicles at the presynaptic membrane. Among the pre-synaptic SNARE proteins, the activation of the Q-SNARE syntaxin1A is a critical event for SNARE complex formation. Activati …
Here, we have used a fluorescent EMSA to reveal a previously uncharacterized binding site for the endosomal Sec1/Munc18 protein, Vps45p, on the syntaxin Tlg2p. We show that a construct lacking the N-peptide of Tlg2p interacts tightly with Vps45p (Fig. 2), demonstrating the presence of a C-terminal binding site. The Vps45p-L117R mutant, which does not bind the N-peptide of Tlg2p, binds to Tlg2p(37-318) with a similar affinity as wild type. Moreover, mutation of Tlg2p residues F9 and L10 to alanine, which disrupts binding of the N-peptide to Vps45p, competes for binding to Vps45p similarly to the N-peptide deletion (Table 1). This Tlg2p-Vps45p interaction explains the lack of a trafficking defect when the Vps45p-L117R mutant is expressed in yeast as the sole copy of Vps45p (13). Our results indicate that abrogation of both the N-peptide and closed conformation binding sites is needed to disrupt Tlg2p function (Fig. 4). Although previous qualitative studies suggested that the Tlg2p N-peptide was ...
The endomembrane system describes the series of organelles and membrane-bound structures within which proteins are synthesized, packaged, and transported to various locations within the cell or are secreted from the plasma membrane. In order to facilitate these activities, trafficking machinery must be involved at the site of vesicle biogenesis at the donor membrane as well as the site of fusion at the target membrane. To achieve this last step, SNARE proteins within both the vesicle and target membranes form tight trans-SNARE complexes, conferring specificity and driving fusion. If additional rounds of transport are to occur, this trafficking machinery must be returned to its original compartment where it can complete its function. Budding yeast, and other eukaryotes, have developed sophisticated mechanisms of recycling SNARE proteins that rely on multiple routes of retrieval and post-translational modifications, like ubiquitination, in order to support efficient recognition and recycling of ...
VAMP2 - VAMP2 (untagged)-Human vesicle-associated membrane protein 2 (synaptobrevin 2) (VAMP2) available for purchase from OriGene - Your Gene Company.
Vamp4 - Vamp4 (untagged) - Mouse vesicle-associated membrane protein 4 (Vamp4), (10ug) available for purchase from OriGene - Your Gene Company.
Complete information for STXBP3 gene (Protein Coding), Syntaxin Binding Protein 3, including: function, proteins, disorders, pathways, orthologs, and expression. GeneCards - The Human Gene Compendium
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How is Vesicle-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor abbreviated? v-SNARE stands for Vesicle-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor. v-SNARE is defined as Vesicle-Soluble NSF (N-Ethylmaleimide-Sensitive Factor) Attachment Protein Receptor somewhat frequently.
TY - JOUR. T1 - Tracking SNARE complex formation in live endocrine cells. AU - An, Seong J.. AU - Almers, Wolfhard. PY - 2004/11/5. Y1 - 2004/11/5. N2 - Syntaxin, synaptosome-associated protein of 25 kD (SNAP25), and vesicle-associated membrane protein/synaptobrevin are collectively called SNAP receptor (SNARE) proteins, and they catalyze neuronal exocytosis by forming a "core complex." The steps in core complex formation are unknown. Here, we monitored SNARE complex formation in vivo with the use of a fluorescent version of SNAP25. In PC12 cells, we found evidence for a syntaxin-SNAP25 complex that formed with high affinity, required only the amino-terminal SNARE motif of SNAP25, tolerated a mutation that blocks formation of other syntaxin-SNAP25 complexes, and assembled reversibly when Ca2+ entered cells during depolarization. The complex may represent a precursor to the core complex formed during a Ca2+-dependent priming step of exocytosis.. AB - Syntaxin, synaptosome-associated protein of 25 ...
In this study, we demonstrated that tomosyn regulates the oligomerization of the SNARE complex and inhibits SNARE-dependent neurotransmitter release. We reconstituted tomosyn-induced oligomerization of the SNARE complex in vitro and showed that the WD-40 repeat domain of tomosyn has an intrinsic ability to catalyze the oligomerization of the SNARE complex. It was previously reported that the C-terminal VLD of tomosyn acts as a SNARE domain competing with VAMP-2 and thereby inhibiting the formation of the SNARE complex (Yokoyama et al., 1999; Pobbati et al., 2004). Consistent with these studies, our in vitro assay showed that the C-terminal VLD of tomosyn inhibits the formation of the SNARE complex. Therefore, we concluded that tomosyn potently inhibits SNARE-dependent synaptic vesicle fusion via both N-terminal WD-40 repeat domain-catalyzed oligomerization of the SNARE complex and C-terminal VLD-based competitive inhibition of SNARE complex formation.. Synaptic efficacy at mossy fiber synapses ...
During synaptic vesicle fusion, the soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) protein syntaxin-1 exhibits two conformations that both bind to Munc18-1: a "closed" conformation outside the SNARE complex and an "open" conformation in the SNARE complex. Although SNARE complexes containing open syntaxin-1 and Munc18-1 are essential for exocytosis, the function of closed syntaxin-1 is unknown. We generated knockin/knockout mice that expressed only open syntaxin-1B. Syntaxin-1BOpen mice were viable but succumbed to generalized seizures at 2 to 3 months of age. Binding of Munc18-1 to syntaxin-1 was impaired in syntaxin-1BOpen synapses, and the size of the readily releasable vesicle pool was decreased; however, the rate of synaptic vesicle fusion was dramatically enhanced. Thus, the closed conformation of syntaxin-1 gates the initiation of the synaptic vesicle fusion reaction, which is then mediated by SNARE-complex/Munc18-1 assemblies. ...