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Introduction

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Membrane fusion is the common mechanism employed by cells for the controlled release of a great variety of substances, including endocrine hormones such as insulin, digestive enzymes, and a vast array of mediators, such as histamine, adrenaline, and many cytokines and growth factors (see Vesicles can bud and fuse with membranes). It permits intercellular communication locally or at a distance. Fusion can be regulated in time and can be highly localized within cells, thereby allowing release to occur in precisely timed spatial patterns. In the nervous system, exquisitely fine temporal control of fusion at precisely determined synaptic contacts allows quantal amounts of neurotransmitter to be released in spatial patterns within neural networks, in turn permitting information to be processed, recombined, and stored. In each case, membrane-bound vesicles containing the material to be secreted fuse with the plasma membrane when required (see The synapse is a model system for exocytosis). As the lipid bilayers of vesicle and plasma membrane merge into one, the lumen of the vesicle becomes continuous with the extracellular space, resulting in the secretion of the stored content by "exocytosis."

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Vesicles also fuse with membranes of organelles, and intracellular transport is a universal and obligatory process for all eukaryotes. A variety of different kinds of vesicles travel through the cytoplasm, executing a complex pattern of secretory, biosynthetic and endocytic protein traffic to deliver distinct groups of proteins and lipids to the different organelles they target for fusion. Biosynthetic transport of many newly synthesized proteins occurs from their site of synthesis in the endoplasmic reticulum via the Golgi stack to the various intracellular compartments where they function. Vesicle transport originating at the plasma membrane, a process called endocytosis, is responsible for internalizing and distributing macromolecules and key nutrients such as vitamins, iron, and cholesterol. Endocytosis also allows the sensitivity of cells to external signals to be dynamically regulated by providing means to control the turnover of signaling receptors (see Receptors recycle via endocytosis).

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By the early 1960s, George Palade had captured and brilliantly interpreted images of "zymogen granules" — vesicles storing digestive enzymes in the pancreas — with their membranes merging with the cell surface in the process of discharging their content. In the decade that followed, Palade discovered the secretory pathway and it became clear that membrane fusion must be highly specific to ensure accurate delivery within the cell (1945). However, the fundamental mechanism of membrane fusion and its exquisite specificity remained a central mystery of cell biology.

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Background

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Figure 1  
Cargo transport between intracellular compartments and membrane fusion requires general cytosolic proteins, such as the N-ethyl-maleimide (NEM)-sensitive fusion protein (NSF). After NEM-inactivation of NSF, vesicles still bud (using cytoplasmic coat proteins, shown in purple) and uncoat, but they fail to fuse and hence can be seen to accumulate using electron microscopy. NSF was purified according to its capacity to restore transport between Golgi cisternae after inhibition by NEM.

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The identification of proteins needed for membrane fusion stemmed from the cell-free reconstitution of protein transport, involving vesicle budding and fusion in the Golgi (1887) (and see The cell-free reconstitution of vesicle transport). The sugar chains of a glycoprotein (in this case, VSV G protein) mature as it is transported between cisternae of isolated Golgi stacks. The extent of this glycosylation is a measure of the amount of transport. In the cell free assay, Golgi membrane transport requires a cytosol fraction and ATP. As diagrammed in Figure 1, transport is prevented when the reaction is treated with the sulfhydryl alkylating reagent N-ethylmaleimide (NEM), which selectively reacts with amino acid side chains containing terminal -SH groups. The N-ethylmaleimide S ensitive Factor (NSF) was purified from cytosol fractions based on its ability to restore transport following NEM inactivation (1883). Electron microscopy and other tests revealed that NSF is required for fusion since vesicles accumulate after NEM inhibition (1890).

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We soon appreciated that NSF is an ATPase required for vesicle fusion at many compartments in the cell, and that it is extremely well conserved in evolution. Sec18p (NSF) from yeast can replace NSF in fusion with the Golgi of higher animals (1949), foreshadowing the universality of the fusion mechanism.

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Figure 2  
Membrane fusion requires soluble NSF attachment proteins (SNAPs). SNAPs function as adaptor proteins, mediating the binding of NSF to compartment-specific SNAP receptors (SNAREs), and were purified on the basis of their ability to bind to SNAP receptors on membranes and thereby also bind NSF to membranes.

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Because NSF is a soluble cytoplasmic protein, it must bind to membranes to function in the fusion process. How this happens was clarified with the identification of Soluble NSF Attachment Protein (SNAP), which was purified according to its ability to bind NSF to Golgi membranes, as diagrammed in Figure 2(782).

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Figure 3  
Cycle of 20S particle assembly and disassembly. NSF, SNAPs and SNAREs form hetero-oligomeric complexes, so-called 20S particles. ATP hydrolysis by NSF dissociates the 20S particles, regenerating the individual components for another round of membrane fusion.

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How, then, does SNAP — which is also a cytosolic protein — bind to membranes? SNAP binds to one or more saturable, high affinity "SNAP REceptors" ("which we termed SNAREs") on Golgi membranes before binding to the ATP-bound form of NSF. This complex of NSF, SNAP and SNARE (see Figure 3) sediments as a 20S particle after extraction from membranes with mild detergents. When NSF hydrolyzes the ATP, it releases itself from the complex (783).

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It seemed likely that SNAREs would be directly inserted into membranes because the SNAP receptors retain their ability to bind SNAP, even after extraction of membranes with strong alkali, a harsh treatment that removes all but integral membrane proteins (1948). That put purification of this membrane protein(s) at the very top of our agenda because of the expectation that lipid bilayer fusion would require membrane-anchored proteins. The SNARE proteins thus became the prime candidates for the fusion proteins.

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The experiment

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The meaning of the seemingly futile cycle of membrane binding and ATPase-driven release of NSF was unclear at the time Söllner joined the Rothman lab as a postdoctoral fellow in 1991. At the time, we imagined that energy from hydrolysis of ATP somehow activated the membrane-anchored SNAREs to power fusion. However, the existence of the cycle had a huge impact on our strategy for identifying the SNAREs. The assembly and disassembly of 20S particles, involving binding and release of NSF from SNAP, respectively, could be exploited as sequential affinity purification steps to isolate SNAREs. Previous experiments had shown that standard chromatographic methods and a single affinity step were inadequate for isolating SNAREs; the 20S ATPase cycle would add a second level of biological specificity.

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SNARE activity could be found in crude membrane fractions from homogenates of various cell lines and animal tissues, in addition to the purified Golgi membranes in which it was originally detected. It turned out that brain homogenates have the highest specific SNARE activity of thetissues that were tested, and large quantities of SNAREs could be easily obtained. These are, of course, the classic criteria for choosing a source for protein purification, but in our case the choice of brain would soon prove to have been mostfortunate for unexpected reasons. Gray matter was homogenized, the total membrane fraction was isolated by centrifugation, and then a "soluble" protein extract was prepared by treating the membrane pellet with a detergent. This detergent extract contained SNARE activity as well as the bulk of integral membrane proteins now "solubilized"; i.e., distributed among micelles of the detergent.

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Figure 4  
Recombinant SNAP, and epitope-tagged NSF were assembled into 20S particles together with SNAREs derived from detergent-solubilized membrane fractions in the presence of the non-hydrolyzable ATP analogue, ATPγS. The 20S particles were then immobilized on beads via an antibody directed to the epitope-tagged NSF, washed in the presence of MgATPγS ("non-specific eluate") and then disassembled in the presence of MgATP, releasing SNAPs and SNAREs ("specific eluate"). NSF remains bound via the antibody to the beads.

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The assembly arm of the NSF cycle was then utilized on a preparative scale as the first of two biologically specific steps, depicted in Figure 4. The idea was that SNAREs would be sequestered from the bulk of membrane protein by incorporation into 20S complexes formed with exogenously added, purified recombinant (bacterially expressed) NSF and SNAP proteins. This incubation would be done in the presence of ATPγS (a nonhydrolyzable analogue of ATP) and in the absence of free magnesium ion (Mg2+ is required for hydrolysis of ATP by NSF) to promote 20S particle assembly. The recombinant NSF was expressed with a short peptide epitope from myc to allow the 20S particles to be isolated with a monoclonal antibody (immobilized on beads) directed against this myc tag (Figure 4).

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The second biologically specific step recapitulated the disassembly of 20S particles. As depicted in Figure 4, SNAREs would be released when the beads are incubated with magnesium ion and ATP to allow NSF to hydrolyze ATP. Recombinant myc-tagged NSF would remain bound to the beads by the antibody, but the recombinant SNAP proteins would be released along with the SNAP binding proteins from the brain membranes.

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Figure 5  
The specific MgATP-eluate was analyzed by polyacrylamide gel electro­phoresis. Proteins were revealed by staining with Coomassie blue and then identified by amino acid sequencing and mass spectroscopy. The bands at the top of the gel were also observed in the nonspecific eluate. (Adapted from 785.)

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Because vesicle fusion occurs at many membrane compartments, we had suspected that cells would have a large family of SNARE proteins, related in sequence and differing in location. We were therefore surprised when the SNAREs derived from whole brain yielded a remarkably simple protein pattern (shown in Figure 5) consisting of only four proteins, each present in the specific (MgATP) eluate and absent from the nonspecific (MgATPγS) eluate.

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Figure 6  
When an action potential moving along a nerve axon reaches a nerve terminal, it causes calcium to enter, which in turn triggers the fusion of synaptic vesicles and the release of neuro­transmitter into the synaptic cleft. The neuro­transmitters bind to specific receptors on the post-synaptic cell, resulting in an altered membrane potential or triggering of a signal transduction pathway, or both. Synaptic vesicle fusion requires the v-SNARE synaptobrevin /VAMP on synaptic vesicles and the t-SNAREs syntaxin and SNAP-25 on the presynaptic plasma membrane.

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The identity and purity of these membrane proteins was established by microsequencing and by mass spectroscopy of peptides derived from the very small amount of material we had isolated. All four SNAREs turned out to be proteins found in synapses (Figure 6). Although they had all previously been cloned and sequenced, their function was still unknown. Two are isoforms of syntaxin, a plasma membrane protein identified by Richard Scheller (1937) based on its ability to bind synaptotagmin, a synaptic vesicle calcium sensor (1941). The third SNARE protein is SNAP-25, short for synaptosome-associated protein of 25 kDa, cloned by Michael Wilson (1944). SNAP-25 mainly resides in the plasma membrane and was originally identified because of its abundance in synapses. Its connection to syntaxin and to membrane fusion was a surprise, as was the coincidental relationship of its acronym to that of the soluble NSF attachment protein, SNAP.

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VAMP/Synaptobrevin-2 was the last SNARE protein to emerge. It had been cloned by DeCamilli and Jahn, and independently by Scheller (1950; 1940). In contrast to SNAP-25 and syntaxin, VAMP resides mainly in synaptic vesicles. The discovery of VAMP in the complex was the lynchpin observation because it immediately suggested how the complex of SNARE proteins (perhaps with NSF and SNAP) could be important for membrane fusions. Since VAMP protrudes from the vesicle membrane into the cytosol, and syntaxin and SNAP-25 likewise protrude from the plasma membrane, a complex involving all three integral membrane proteins could bring the vesicle to the plasma membrane, placing their lipid bilayers within molecular contact range (Figure 6).

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The SNARE hypothesis

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We then went on to interpret the SNARE complex from a very broad perspective instead of limiting ourselves to the special point-of-view of synaptic vesicle exocytosis. First principles require that vesicles and targets somehow be marked to indicate which vesicles will fuse where. This, in turn, indicates that vesicle and target markers must be matched pairwise. We suggested that the simplest mechanism for matching is self-assembly, in which only matching pairs of "cognate" vesicle ("v") and target ("t") markers bind each other between membranes, thereby forming a "v-t" complex prerequisite for membrane fusion.

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Based on our cognate vesicle and target marker concept, we proposed the "SNARE hypothesis" in which the SNAREs are the vesicle and target markers, which we termed v-SNAREs and t-SNAREs (see SNARES are responsible for membrane fusion). VAMP is the v-SNARE of the synaptic vesicle; syntaxin and SNAP-25 are the subunits of the cognate t-SNARE in the plasma membrane. The SNARE hypothesis provides the framework to generalize our results. We suggested that each type of vesicle in the cell would have its own characteristic v-SNARE, a homologue of VAMP, and that each target membrane in the cell would be marked by a characteristic t-SNARE, having subunits homologous to syntaxin and SNAP-25. In addition, we suggested that "In the simplest view, that is, if there were no other source of specificity, only when complementary v-SNARE and t-SNARE pairs engage would a productive fusion event be initiated" (785).

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Consistent with our simple model, VAMP and syntaxin are membrane-anchored proteins with cytoplasmic domains, and SNAP-25 is anchored to the cytoplasmic side of the plasma membrane via covalently attached fatty acids. Close to equimolar amounts of VAMP, syntaxin (its two isoforms considered together) and SNAP-25 were recovered in the isolated complexes. Furthermore, the SNARE proteins were isolated because they bind to and form a 20S particle with NSF and SNAPs, which are known to function in fusion, implying that SNAREs also function in fusion. The SNARE complex progressed from first discovery to final publication in a dizzying sweep lasting only 5 weeks.

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The legacy

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At the time of our experiment, membrane fusion was complex and confusing because a conceptual framework with which to organize the continuously increasing list of genes and sequences was lacking. A great many genes and proteins of yeast and animal cells, including neurons, were implicated as being somehow involved in the overall process of vesicle transport or fusion or its regulation. It was readily appreciated that many of these genes and proteins belong to evolutionarily conserved families affecting different transport steps (reviewed in 1938). A dozen or more proteins were known to reside in the synaptic vesicle alone. But it was guess work as to which proteins could catalyze fusion or provide for its specificity, as distinct from affecting fusion indirectly at the level of cellular regulation, and many proteins had been considered to be candidates for fusion, including at one time or another synaptophysin, synaptoporin and SV2. Interestingly, although VAMP and syntaxin were seen to be important players, they were not highlighted in this context and not suggested to form a complex, and SNAP-25 was not connected to exocytosis.

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The primary impact of our paper stemmed from its combination of an unexpected discovery — the SNARE complex — and a broad and clearly stated concept — the SNARE hypothesis — deduced from it. Its impact was amplified because the discovery of the SNARE complex firmly linked three fields (cell biology (vesicle transport), physiology (endocrine and exocrine secretion), and neurobiology (synaptic transmission)), three disciplines (cell-free biochemistry, yeast genetics, and electrophysiology), and many favorite cells and organisms. As a result our paper changed the focus of cell biology, away from differences in physiology and regulation and on to core machinery and universal mechanisms.

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In follow-up work we found that NSF and SNAP function to disrupt the SNARE complex using energy derived by ATP hydrolysis, and it was later shown that SNAP and NSF are not directly involved in bilayer fusion (1943). This focused attention on the simplest remaining possibility, that the SNARE complex is all that is needed to mediate fusion. However, NSF and SNAP play a critical role in sustaining ongoing fusion. They separate v-SNAREs from t-SNAREs after fusion (i.e., when they reside in the same bilayer), but not during fusion (i.e., when they are paired between bilayers) (1947). This allows NSF and SNAP to recycle SNARE complexes after fusion while sparing fusion in progress.

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The SNARE complex is extraordinarily stable, resisting heat denaturation up to 90°C (1951). The rod-like structure of the SNARE complex with its membrane anchors at one end, implies that it could bring two membranes into close contact and it was suggested that the binding energy from SNARE assembly could drive bilayer fusion (1942).

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Figure 7  
v-SNAREs (in green) on a vesicle bind to their cognate t-SNAREs (in red) on the target membrane, forming specific SNAREpins that then fuse the two membranes. For simplicity, the t-SNARE is shown as a single elongated rod, although it is now known to contribute three α-helices to a four-helix v-t-SNARE bundle. Other proteins regulate the assembly and disassembly of SNAREpins and thus control membrane fusion.

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A direct test of the possibility that the SNARE complex is the active principle of fusion, could only come from assessing this function in the absence of all other proteins. Reconstituting recombinant exocytic/neuronal SNAREs into liposomes established that the pairing of cognate SNARES between lipid bilayers indeed results in spontaneous membrane fusion (786) (Figure 7). Thus, when complementary v-SNARE and t-SNARE pairs engage, a productive fusion event is not only initiated as we had first imagined but it is also completed.

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The SNARE hypothesis triggered extensive research that led to the identification of many more SNAREs, which as predicted localize and function at compartments engaging in fusion (1939). In the most direct test of the SNARE hypothesis to date (this is being written in 2001), it was established that specificity for membrane fusion is encoded in the physical chemistry of the isolated SNARE proteins (1183). At present, a total of 275 combinations of the potential v-SNAREs and t-SNAREs encoded in the genome of yeast, representing ER, Golgi, plasma membrane, endosomes, and vacuoles (lysosomes), have been tested for fusion. Of these, only 9 combinations (~3%) are fusogenic and all but one (~0.4%) correspond to known transport pathways. Virtually without exception, fusion only takes place with the rare combinations of v- and t-SNAREs that are drawn from compartments connected by vesicle shuttles in the living cell. Put differently, a physical chemist armed only with the DNA sequence of yeast and the SNARE hypothesis could test isolated SNAREs to read out the fusion potential and transport pathways allowed in the cell with at least 99.6% accuracy.

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Current research focuses on the detailed mechanisms by which the SNARE complex is regulated by additional proteins to permit membrane fusion to be spatially and temporally controlled, and how these mechanisms are employed in organismal physiology and pathology. Because t-SNAREs are intrinsically autoinhibited (1946) they can be locally activated, thereby allowing vesicles to be targeted to a distinct region within a membrane (such as the leading edge of plasma membrane of a moving cell) and also adding a layer of specificity. This occurs when vesicles are initially captured by compartment-specific protein tethers, and it appears that vesicles must be "tethered" before they can be "SNAREd" (1892).

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The authors

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James E. Rothman is Vice Chairman of the Sloan-Kettering Institute of Memorial Sloan-Kettering Cancer Center and founding Chairman of its Cellular Biochemistry and Biophysics Program. Prior to his current appointment, Rothman was the E.R. Squib Professor of Molecular Biology at Princeton University (1988-91) and Professor of Biochemistry at Stanford University School of Medicine (1978-88). He received his B.A. from Yale University in physics (1971), studied medicine at Harvard Medical School (1971-73), received his Ph.D. in biochemistry from Harvard (1976), and was a postdoctoral fellow at MIT (1976-78). Among other honors, Rothman has received Canada's Gairdner Foundation International Award (1996), Saudi Arabia's King Faisal International Prize (1996), the National Academy of Sciences' Lounsbery Award, The Netherlands' Heineken Prize (2000), and Germany's Otto-Warburg Medal (2001). He is a Member of the U.S. National Academy of Sciences (1993) and its Institute of Medicine (1995). His current work centers on the biophysical mechanism and regulation of membrane fusion, and the design of engineered fluorescent indicator proteins for monitoring the activity of signaling and transport pathways in cells and tissues, including those of the nervous system.
Thomas H. Söllner graduated 1987 at the Ludwig Maximilians University Munich and received his Ph.D. in 1991 after training in the laboratory of Walter Neupert, where he identified and analyzed the protein import machinery in the mitochondrial outer membrane. From 1991-93, Söllner was a postdoctoral fellow in James Rothman's laboratory at the Sloan-Kettering Institute, New York, resulting in the SNARE hypothesis. Later, he joined the faculty of the Cellular Biochemistry and Biophysics Program at Sloan-Kettering where his laboratory currently studies the regulation of membrane fusion using synaptic transmission as a model system.


James E. Rothman
Cellular Biochemistry & Biophysics Program
Sloan-Kettering Institute
1275 York Avenue, Box 521
New York, NY 10021
USA
Phone: 001 212 639 8598
Fax: 001 212 717 3604
Email: j-rothman@ski.mskcc.org


Thomas H. Söllner
Cellular Biochemistry & Biophysics Program
Sloan-Kettering Institute
1275 York Avenue, Box 521
New York, NY 10021
USA
Phone: 001 212 639 5172
Fax: 001 212 717 3604
E-mail: t-sollner@ski.mskcc.org

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Last Revised on September 24, 2004

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reviews
  • 1892 Mellman, I. and Warren, G. (2000).  The road taken: past and future foundations of membrane traffic.  Cell 100, 99-112.  PubMed   Journal
  • 1938 Bennett, M. K. and Scheller, R. H. (1993).  The molecular machinery for secretion is conserved from yeast to neurons.  Proc. Natl. Acad. Sci. USA 90, 2559-2563.  PubMed   Journal
  • 1945 Palade, G. (1975).  Intracellular aspects of the process of protein synthesis.  Science 189, 347-358.  PubMed  
reviews
  • 782 Clary, D. O., Griff, I. C., and Rothman, J. E. (1990).  SNAPs, a family of NSF attachment proteins involved in intracellular membrane fusion in animals and yeast.  Cell 61, 709-21.  PubMed   Journal
  • 783 Wilson, D. W., Whiteheart, S. W., Wiedmann, M., Brunner, M., and Rothman, J. E. (1992).  A multisubunit particle implicated in membrane fusion.  J. Cell Biol. 117, 531-538.  PubMed  
  • 785 Söllner, T., Whiteheart, S. W., Brunner, M., Erdjument-Bromage, H., Geromanos, S., Tempst, P., and Rothman, J. E. (1993).  SNAP receptors implicated in vesicle targeting and fusion.  Nature 362, 318-324.  PubMed   Journal
  • 786 Weber, T., Zemelman, B., McNew, J., Westermann, B., Gmachl, M., Parlati, F., Sollner, T.H., Rothman, J.E. (1998).  SNAREpins: minimal machinery for membrane fusion.  Cell 92, 759-772.  PubMed   Journal
  • 1183 McNew, J. A., Parlati, F., Fukuda, R., Johnston, R. J., Paz, K., Paumet, F., Sollner, T. H., and Rothman, J. E. (2000).  Compartmental specificity of cellular membrane fusion encoded in SNARE proteins.  Nature 407, 153-159.  PubMed   Journal
  • 1883 Block, M. R., Glick, B. S., Wilcox, C. A., Wieland, F. T., and Rothman, J. E. (1988).  Purification of an N-ethylmaleimide-sensitive protein catalyzing vesicular transport.  Proc. Natl. Acad. Sci. USA 85, 7852-7856.  PubMed  
  • 1887 Fries, E. and Rothman, J. E. (1980).  Transport of vesicular stomatitis virus glycoprotein in a cell-free extract.  Proc. Natl. Acad. Sci. USA 77, 3870-3874.  PubMed  
  • 1890 Malhotra, V., Orci, L., Glick, B. S., Block, M. R., and Rothman, J. E. (1988).  Role of an N-ethylmaleimide-sensitive transport component in promoting fusion of transport vesicles with cisternae of the Golgi stack.  Cell 54, 221-227.  PubMed   Journal
  • 1937 Bennett, M. K., Calakos, N., and Scheller, R. H. (1992).  Syntaxin: a synaptic protein implicated in docking of synaptic vesicles at presynaptic active zones.  Science 257, 255-259.  PubMed  
  • 1939 Bock, J. B., Matern, H. T., Peden, A. A., and Scheller, R. H. (2001).  A genomic perspective on membrane compartment organization.  Nature 409, 839-841.  PubMed   Journal
  • 1940 Elferink, L. A., Trimble, W. S., and Scheller, R. H. (1989).  Two vesicle-associated membrane protein genes are differentially expressed in the rat central nervous system.  J. Biol. Chem. 264, 11061-11064.  PubMed   Journal
  • 1941 Geppert, M., Goda, Y., Hammer, R. E., Li, C., Rosahl, T. W., Stevens, C. F., and Sudhof, T. C. (1994).  Synaptotagmin I: a major Ca2+ sensor for transmitter release at a central synapse.  Cell 79, 717-727.  PubMed   Journal
  • 1942 Hanson, P. I., Roth, R., Morisaki, H., Jahn, R., and Heuser, J. E. (1997).  Structure and conformational changes in NSF and its membrane receptor complexes visualized by quick-freeze/deep-etch electron microscopy.  Cell 90, 523-535.  PubMed   Journal
  • 1943 Mayer, A., Wickner, W., and Haas, A. (1996).  Sec18p (NSF)-driven release of Sec17p (alpha-SNAP) can precede docking and fusion of yeast vacuoles.  Cell 85, 83-94.  PubMed   Journal
  • 1944 Oyler, G. A., Higgins, G. A., Hart, R. A., Battenberg, E., Billingsley, M., Bloom, F. E., and Wilson, M. C. (1989).  The identification of a novel synaptosomal-associated protein, SNAP-25, differentially expressed by neuronal subpopulations.  J. Cell Biol. 109, 3039-3052.  PubMed  
  • 1946 Parlati, F., Weber, T., McNew, J. A., Westermann, B., Sollner, T. H., and Rothman, J. E. (1999).  Rapid and efficient fusion of phospholipid vesicles by the alpha-helical core of a SNARE complex in the absence of an N-terminal regulatory domain.  Proc. Natl. Acad. Sci. USA 96, 12565-12570.  PubMed   Journal
  • 1947 Weber, T., Parlati, F., McNew, J. A., Johnston, R. J., Westermann, B., Sollner, T. H., and Rothman, J. E. (2000).  SNAREpins are functionally resistant to disruption by NSF and alphaSNAP.  J. Cell Biol. 149, 1063-1072.  PubMed   Journal
  • 1948 Weidman, P. J., Melancon, P., Block, M. R., and Rothman, J. E. (1989).  Binding of an N-ethylmaleimide-sensitive fusion protein to Golgi membranes requires both a soluble protein(s) and an integral membrane receptor.  J. Cell Biol. 108, 1589-1596.  PubMed  
  • 1949 Wilson, D. W., Wilcox, C. A., Flynn, G. C., Chen, E., Kuang, W. J., Henzel, W. J., Block, M. R., Ullrich, A., and Rothman, J. E. (1989).  A fusion protein required for vesicle-mediated transport in both mammalian cells and yeast.  Nature 339, 355-359.  PubMed   Journal
  • 1950 Baumert, M., Maycox, P. R., Navone, F., De Camilli, P., and Jahn, R. (1989).  Synaptobrevin: an integral membrane protein of 18,000 daltons present in small synaptic vesicles of rat brain.  EMBO J. 8, 379-384.  PubMed  
  • 1951 Hayashi, T., McMahon, H., Yamasaki, S., Binz, T., Hata, Y., Sudhof, T. C., and Niemann, H. (1994).  Synaptic vesicle membrane fusion complex: action of clostridial neurotoxins on assembly.  EMBO J. 13, 5051-5061.  PubMed  

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