A genomic perspective on membrane compartment organization

Bock, Jason B.; Matern, Hugo; Peden, Andrew A.; Scheller, Richard H.

doi:10.1038/35057024

Cited by 619 publications

(539 citation statements)

References 8 publications

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“…Interestingly, expression of a dominant-interfering Exo70 protein or siRNA-mediated knockdowns did not prevent GLUT4 vesicle trafficking to the plasma membrane but did inhibit GLUT4 plasma membrane fusion whereas over expression of Sec6 and Sec8 enhanced GLUT4 translocation to the plasma membrane [33,35]. Although these data indicate that the Exocyst complex plays an important role in the insulin-regulated plasma membrane docking/tethering of GLUT4 vesicles, it is well established the physiologic minimal fusion machinery is dependent upon the assembly of the SNARE complex [36][37][38] SNARE proteins can be generally classified as v-SNAREs (or R-SNAREs) that possess a single coil-coiled domain and a transmembrane domain that are localized in vesicle compartment [39][40][41][42]. The second family, t-SNAREs (or Q-SNAREs) are dimeric, with one partner belongs to the family of syntaxin isoforms and the second partner belonging to the family of SNAP isoform.…”

Section: Glut4 Vesicle Docking and Plasma Membrane Fusionmentioning

confidence: 99%

Ins (endocytosis) and outs (exocytosis) of GLUT4 trafficking

Hou

Pessin

2007

Current Opinion in Cell Biology

132

116

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SummaryGlucose transporter 4 (GLUT4) is the major insulin regulated glucose transporter expressed mainly in muscle and adipose tissue. GLUT4 is stored in a poorly characterized intracellular vesicular compartment and translocates to the cell surface in response to insulin stimulation resulting in increase glucose uptake. This process is essential for the maintenance of normal glucose homeostasis and involves a complex interplay of trafficking events and intracellular signaling cascades. Recent studies have identified sortilin as an essential element for the formation of GLUT4 storage vesicles during adipogenesis and GGA (Golgi-localized γ-ear-containing Arf-binding protein) as a key coat adaptor for the entry of newly synthesized GLUT4 into the specialized compartment. Insulinstimulated GLUT4 translocation from this compartment to the plasma membrane appears to require the Akt/protein kinase B substrate, termed AS160 (Akt Substrate of 160 kDa). In addition, the VPS9 domain-containing protein Gapex-5 in complex with CIP4 appears to function as a Rab31 guanylnucleotide exchange factor that is necessary for insulin-stimulated GLUT4 translocation. Here we attempt to summaries recent advances in GLUT4 vesicle biogenesis, intracellular trafficking and membrane fusion.

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Section: Glut4 Vesicle Docking and Plasma Membrane Fusionmentioning

confidence: 99%

Ins (endocytosis) and outs (exocytosis) of GLUT4 trafficking

Hou

Pessin

2007

Current Opinion in Cell Biology

132

116

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“…There are 36 SNAREs in humans [2,14]. Individuals of the SNARE family localize to distinct subcellular organelles in the secretory pathway, suggesting that they have selective roles in specific intracellular trafficking steps [15].…”

Section: Introductionmentioning

confidence: 99%

Membrane fusion by VAMP3 and plasma membrane t-SNAREs

Hardee

Minnear

2007

Experimental Cell Research

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Pairing of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins on vesicles (v-SNAREs) and SNARE proteins on target membranes (t-SNAREs) mediates intracellular membrane fusion. VAMP3/cellubrevin is a v-SNARE that resides in recycling endosomes and endosome-derived transport vesicles. VAMP3 has been implicated in recycling of transferrin receptors, secretion of α-granules in platelets, and membrane trafficking during cell migration. Using a cell fusion assay, we examined membrane fusion capacity of the ternary complexes formed by VAMP3 and plasma membrane t-SNAREs syntaxin1, syntaxin4, SNAP-23 and SNAP-25. VAMP3 forms fusogenic pairing with t-SNARE complexes syntaxin1/SNAP-25, syntaxin1/SNAP-23 and syntaxin4/SNAP-25, but not with syntaxin4/SNAP-23. Deletion of the Nterminal domain of syntaxin4 enhanced membrane fusion more than two fold, indicating that the Nterminal domain negatively regulates membrane fusion. Differential membrane fusion capacities of the ternary v-/t-SNARE complexes suggest that transport vesicles containing VAMP3 have distinct membrane fusion kinetics with domains of the plasma membrane that present different t-SNARE proteins.

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“…These proteins are members of the SNARE protein family that are involved in all fusion events of the secretory pathway. SNAREs are characterized by stretches of 60-70 amino acids arranged in heptad repeats, termed SNARE motifs (Weimbs et al, 1997;Fasshauer et al, 1998b;Bock et al, 2001;Day et al, 2006). Syntaxin and synaptobrevin each contain a single SNARE motif that is located adjacent to a C-terminal transmembrane domain.…”

Section: Introductionmentioning

confidence: 99%

Determinants of Synaptobrevin Regulation in Membranes

Siddiqui

Vites

Stein³

et al. 2007

MBoC

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Neuronal exocytosis is driven by the formation of SNARE complexes between synaptobrevin 2 on synaptic vesicles and SNAP-25/syntaxin 1 on the plasma membrane. It has remained controversial, however, whether SNAREs are constitutively active or whether they are down-regulated until fusion is triggered. We now show that synaptobrevin in proteoliposomes as well as in purified synaptic vesicles is constitutively active. Potential regulators such as calmodulin or synaptophysin do not affect SNARE activity. Substitution or deletion of residues in the linker connecting the SNARE motif and transmembrane region did not alter the kinetics of SNARE complex assembly or of SNARE-mediated fusion of liposomes. Remarkably, deletion of C-terminal residues of the SNARE motif strongly reduced fusion activity, although the overall stability of the complexes was not affected. We conclude that although complete zippering of the SNARE complex is essential for membrane fusion, the structure of the adjacent linker domain is less critical, suggesting that complete SNARE complex assembly not only connects membranes but also drives fusion. INTRODUCTIONCommunication between neurons is mediated by neurotransmitters that are released from presynaptic nerve endings by Ca 2ϩ -dependent exocytosis of synaptic vesicles. Exocytotic fusion of the vesicle with the synaptic plasma membrane is mediated by the proteins synaptobrevin 2/VAMP2, SNAP-25, and syntaxin 1 (Jahn and Scheller, 2006;Rizo et al., 2006). These proteins are members of the SNARE protein family that are involved in all fusion events of the secretory pathway. SNAREs are characterized by stretches of 60-70 amino acids arranged in heptad repeats, termed SNARE motifs (Weimbs et al., 1997;Fasshauer et al., 1998b;Bock et al., 2001;Day et al., 2006). Syntaxin and synaptobrevin each contain a single SNARE motif that is located adjacent to a C-terminal transmembrane domain. In contrast, SNAP-25 contains two SNARE motifs connected by a palmitoylated linker region that serves as membrane anchor.Synaptobrevin resides in synaptic vesicles, whereas SNAP-25 and syntaxin 1 reside in the plasma membrane. The SNARE motifs of syntaxin, SNAP-25, and synaptobrevin readily assemble into quarternary bundles of ␣-helices (Fasshauer et al., 1997;Sutton et al., 1998). Assembly would thus lead to a tight connection between the membranes. According to this view, assembly is nucleated at the Nterminal ends of the SNARE-motifs and proceeds toward the C-terminal membrane anchor ("zippering"), resulting in a strained "trans"-complex . During membrane merger, the trans-complex would relax into a "cis"-complex in which the transmembrane domains are aligned in parallel. To regenerate the SNAREs for another round of fusion, SNARE complexes need to be disassembled by the AAAϩ-ATPase NEM-sensitive factor (NSF) in conjunction with cofactors termed soluble NSF attachment proteins (SNAPs; Sollner et al., 1993).Although the "zippering" hypothesis of SNARE function has received a lot of experimental support, it is still unclear...

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A genomic perspective on membrane compartment organization

Cited by 619 publications

References 8 publications

Ins (endocytosis) and outs (exocytosis) of GLUT4 trafficking

Ins (endocytosis) and outs (exocytosis) of GLUT4 trafficking

Membrane fusion by VAMP3 and plasma membrane t-SNAREs

Determinants of Synaptobrevin Regulation in Membranes

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