Subunit Structure of a Mammalian ER/Golgi SNARE Complex

Xu, Dalu; Joglekar, Ashwini P.; Williams, Antionette L.; Hay, Jesse

doi:10.1074/jbc.m007684200

Cited by 113 publications

(170 citation statements)

References 37 publications

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“…In one, Sec22b was the v-SNARE, and syntaxin 5, membrin, and rBet1 were the t-SNAREs in NRK cells (29). However, in intestine, we found that Sec22b antibodies did not affect PCTV fusion with intestinal cis-Golgi.…”

Section: Discussionmentioning

confidence: 40%

The Identification of a Novel Endoplasmic Reticulum to Golgi SNARE Complex Used by the Prechylomicron Transport Vesicle

Siddiqi

Mahan²,

Peggs

et al. 2006

Journal of Biological Chemistry

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Dietary long chain fatty acids are absorbed in the intestine, esterified to triacylglycerol, and packaged in the unique lipoprotein of the intestine, the chylomicron. The rate-limiting step in the transit of chylomicrons through the enterocyte is the exit of chylomicrons from the endoplasmic reticulum in prechylomicron transport vesicles (PCTV) that transport chylomicrons to the cis-Golgi. Because chylomicrons are 250 nm in average diameter and lipid absorption is intermittent, we postulated that a unique SNARE pairing would be utilized to fuse PCTV with their target membrane, cis-Golgi. PCTV loaded with [ 3 H]triacylglycerol were incubated with cis-Golgi and were separated from the Golgi by a sucrose step gradient. PCTV-chylomicrons acquire apolipoprotein-AI (apoAI) only after fusion with the Golgi. PCTV became isodense with Golgi upon incubation and were considered fused when their cargo chylomicrons acquired apoAI but docked when they did not. PCTV, docked with cis-Golgi, were solubilized in 2% Triton X-100, and proteins were immunoprecipitated using VAMP7 or rBet1 antibodies. In both cases, a 112-kDa complex was identified in nonboiled samples that dissociated upon boiling. The constituents of the complex were VAMP7, syntaxin 5, vti1a, and rBet1. Antibodies to each SNARE component significantly inhibited fusion of PCTV with cis-Golgi. Membrin, Sec22b, and Ykt6 were not found in the 112-kDa complex. We conclude that the PCTV-cisGolgi SNARE complex is composed of VAMP7, syntaxin 5, Bet1, and vti1a.

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Section: Discussionmentioning

confidence: 40%

The Identification of a Novel Endoplasmic Reticulum to Golgi SNARE Complex Used by the Prechylomicron Transport Vesicle

Siddiqi

Mahan²,

Peggs

et al. 2006

Journal of Biological Chemistry

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“…For example, in the case of SNARE-mediated endoplasmic reticulumGolgi transport, the mammalian syn5⅐rbet1⅐membrin⅐sec22b complex can only be formed in vitro if sec22b is present while the others assemble (48). In other words, sec22b cannot bind to a preassembled mixture of syn5, membrin, and rbet1.…”

Section: Discussionmentioning

confidence: 99%

Crystal Structure and Biophysical Properties of a Complex between the N-terminal SNARE Region of SNAP25 and Syntaxin 1a

Misura

Gonzalez

May

et al. 2001

Journal of Biological Chemistry

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SNARE proteins are required for intracellular membrane fusion. In the neuron, the plasma membrane SNAREs syntaxin 1a and SNAP25 bind to VAMP2 found on neurotransmitter-containing vesicles. These three proteins contain "SNARE regions" that mediate their association into stable tetrameric coiled-coil structures. Syntaxin 1a contributes one such region, designated H3, and SNAP25 contributes two SNARE regions to the fusogenic complex with VAMP2. Syntaxin 1a H3 (syn1aH3) and SNAP25 can form a stable assembly, which can then be bound by VAMP2 to form the full SNARE complex. Here we show that syn1aH3 can also form a stable but kinetically trapped complex with the N-terminal SNARE region of SNAP25 (S25N). The crystal structure of this complex reveals an extended parallel four-helix bundle similar to that of the core SNARE and the syn1aH3⅐SNAP25 complexes. The inherent ability of syn1aH3 and S25N to associate stably in vitro implies that the intracellular fusion machinery must prevent formation of, or remove, any nonproductive complexes. Comparison with the syn1aH3⅐SNAP25 complex suggests that the linkage of the N-and C-terminal SNAP25 SNARE regions is kinetically advantageous in preventing formation of the non-productive syn1aH3⅐S25N complex. We also demonstrate that the syn1aH3⅐S25N complex can be disassembled by ␣-SNAP and N-ethylmaleimide-sensitive factor.Eukaryotic cells maintain highly organized membrane structures to perform essential cellular functions such as protein synthesis, modification, and degradation. Communication between these membrane compartments is essential to ensure that proteins and other molecules are transported and segregated into appropriate organelles within the cell. This is achieved through cargo-containing vesicles that bud from donor membranes and are transported to acceptor membranes where they fuse. Such a process allows local rearrangement of lipid bilayers while maintaining the overall structural integrity of the membrane compartment. Membrane fusion is mediated in part by a large family of compartment-specific proteins known as SNAREs 1 (soluble NSF attachment protein receptors) that are localized on vesicle or target membranes (1, 2).In neurons, the SNAREs syntaxin 1a (syn1a), SNAP25, and VAMP2 participate in fusing neurotransmitter-filled vesicles with the plasma membrane of the cell, allowing neurotransmitter molecules to be released into the synaptic cleft. VAMP2 (also known as synaptobrevin) is found on the vesicle membrane and contains a characteristic "SNARE region" heptad repeat sequence followed by a single C-terminal membranespanning segment (3). Syntaxin 1a and SNAP25 are localized to the presynaptic membrane. The primary structure of syntaxin 1a consists of an N-terminal domain termed Habc, a SNARE region termed H3, and a single C-terminal membranespanning anchor (4, 5). SNAP25 contains two SNARE regions, designated S25N and S25C, that are separated by a linker region containing four palmitoylated cysteines that tether the protein to the membrane (6, 7). The four SNARE re...

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“…One of the best characterized SNARE complexes is composed of Bet1, ERS24, membrin, and syntaxin 5 (1). It controls the fusion of endoplasmic reticulum (ER)-derived vesicles with the cis-Golgi, and it is generally believed that Bet1 is the v-SNARE subunit in this complex (1), although some have proposed that ERS24 might be the v-SNARE (2,3). At least one other SNARE complex (GS15-GOS28-syntaxin5-Ykt6) is present in the Golgi apparatus, but this complex is more concentrated on the trans face and might control intra-Golgi transport (either anterograde or retrograde) (4), or possibly transport between the Golgi apparatus and endosomes (5).…”

mentioning

confidence: 99%

Dynamic transport of SNARE proteins in the Golgi apparatus

Cosson

Ravazzola

Varlamov

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Localization of a membrane protein in a subcellular compartment can be achieved by its retention in the compartment or by its continuous transport toward this compartment. Previous results have suggested that specific enzymes are localized in the Golgi apparatus at least in part by selective retention and exclusion from transport vesicles. However, the function of some Golgi SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins is not compatible with their exclusion from transport vesicles. To help understand the mechanism accounting for the localization of SNARE proteins in the Golgi apparatus, we analyzed their lateral distribution in the Golgi cisternae and their incorporation into transport vesicles. According to our results, all SNARE proteins are efficiently incorporated into transport vesicles, indicating that the localization of SNARE proteins in the Golgi apparatus is not based on a static retention mechanism. Detailed analysis suggested that incorporation into transport vesicles was more efficient for SNARE proteins restricted to the cis face of the Golgi as compared with SNAREs present at the trans face. Furthermore, overexpression of a cis-Golgi SNARE protein altered concomitantly its incorporation in transport vesicles and its intra-Golgi localization. These observations suggest that, contrary to resident Golgi enzymes, SNARE proteins are localized in the Golgi apparatus as the result of a dynamic transport equilibrium.cisternal maturation ͉ glycosyltransferase ͉ secretion ͉ vesicular transport ͉ membrane sorting

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Subunit Structure of a Mammalian ER/Golgi SNARE Complex

Cited by 113 publications

References 37 publications

The Identification of a Novel Endoplasmic Reticulum to Golgi SNARE Complex Used by the Prechylomicron Transport Vesicle

The Identification of a Novel Endoplasmic Reticulum to Golgi SNARE Complex Used by the Prechylomicron Transport Vesicle

Crystal Structure and Biophysical Properties of a Complex between the N-terminal SNARE Region of SNAP25 and Syntaxin 1a

Dynamic transport of SNARE proteins in the Golgi apparatus

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