Regulation of SNAP-25 trafficking and function by palmitoylation

2010 ◽  
Vol 38 (1) ◽  
pp. 163-166 ◽  
Author(s):  
Jennifer Greaves ◽  
Gerald R. Prescott ◽  
Oforiwa A. Gorleku ◽  
Luke H. Chamberlain

The SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) protein SNAP-25 (25 kDa synaptosome-associated protein) is essential for regulated exocytosis in neuronal and neuroendocrine cells. Whereas the majority of SNARE proteins contain transmembrane domains, SNAP-25 is instead anchored to membranes by the palmitoylation of a central cysteine-rich region. In this review, we discuss the mechanisms of SNAP-25 palmitoylation and how this modification regulates the intracellular trafficking and exocytotic function of this essential protein.

2004 ◽  
Vol 384 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Michael VEIT

The yeast SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) protein Ykt6 was shown to mediate palmitoylation of the fusion factor Vac8 in a reaction essential for the fusion of vacuoles. Here I present evidence that hYkt6 (human Ykt6) has self-palmitoylating activity. Incubation of recombinant hYkt6 with [3H]Pal-CoA ([3H]palmitoyl-CoA) leads to covalent attachment of palmitate to C-terminal cysteine residues. The N-terminal domain of human Ykt6 contains a Pal-CoA binding site and is required for the reaction.


2000 ◽  
Vol 149 (5) ◽  
pp. 1063-1072 ◽  
Author(s):  
Thomas Weber ◽  
Francesco Parlati ◽  
James A. McNew ◽  
Robert J. Johnston ◽  
Benedikt Westermann ◽  
...  

SNARE (SNAP [soluble NSF {N-ethylmaleimide–sensitive fusion protein} attachment protein] receptor) proteins are required for many fusion processes, and recent studies of isolated SNARE proteins reveal that they are inherently capable of fusing lipid bilayers. Cis-SNARE complexes (formed when vesicle SNAREs [v-SNAREs] and target membrane SNAREs [t-SNAREs] combine in the same membrane) are disrupted by the action of the abundant cytoplasmic ATPase NSF, which is necessary to maintain a supply of uncombined v- and t-SNAREs for fusion in cells. Fusion is mediated by these same SNARE proteins, forming trans-SNARE complexes between membranes. This raises an important question: why doesn't NSF disrupt these SNARE complexes as well, preventing fusion from occurring at all? Here, we report several lines of evidence that demonstrate that SNAREpins (trans-SNARE complexes) are in fact functionally resistant to NSF, and they become so at the moment they form and commit to fusion. This elegant design allows fusion to proceed locally in the face of an overall environment that massively favors SNARE disruption.


1997 ◽  
Vol 272 (44) ◽  
pp. 28036-28041 ◽  
Author(s):  
Dirk Fasshauer ◽  
Henning Otto ◽  
William K. Eliason ◽  
Reinhard Jahn ◽  
Axel T. Brünger

2010 ◽  
Vol 188 (4) ◽  
pp. 537-546 ◽  
Author(s):  
Ravi Manjithaya ◽  
Christophe Anjard ◽  
William F. Loomis ◽  
Suresh Subramani

In contrast to the enormous advances made regarding mechanisms of conventional protein secretion, mechanistic insights into the unconventional secretion of proteins are lacking. Acyl coenzyme A (CoA)–binding protein (ACBP; AcbA in Dictyostelium discoideum), an unconventionally secreted protein, is dependent on Golgi reassembly and stacking protein (GRASP) for its secretion. We discovered, surprisingly, that the secretion, processing, and function of an AcbA-derived peptide, SDF-2, are conserved between the yeast Pichia pastoris and D. discoideum. We show that in yeast, the secretion of SDF-2–like activity is GRASP dependent, triggered by nitrogen starvation, and requires autophagy proteins as well as medium-chain fatty acyl CoA generated by peroxisomes. Additionally, a phospholipase D implicated in soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor–mediated vesicle fusion at the plasma membrane is necessary, but neither peroxisome turnover nor fusion between autophagosomes and the vacuole is essential. Moreover, yeast Acb1 and several proteins required for its secretion are necessary for sporulation in P. pastoris. Our findings implicate currently unknown, evolutionarily conserved pathways in unconventional secretion.


2005 ◽  
Vol 72 ◽  
pp. 77-86 ◽  
Author(s):  
J. Paul Luzio ◽  
Paul R. Pryor ◽  
Sally R. Gray ◽  
Matthew J. Gratian ◽  
Robert C. Piper ◽  
...  

In the late endocytic pathway, it has been proposed that endocytosed macromolecules are delivered to a proteolytic environment by 'kiss-and-run' events or direct fusion between late endosomes and lysosomes. To test whether the fusion hypothesis accounts for delivery to lysosomes in living cells, we have used confocal microscopy to examine content mixing between lysosomes loaded with rhodamine-dextran and endosomes subsequently loaded with Oregon-Green-dextran. Both kissing and explosive fusion events were recorded. Data from cell-free content-mixing assays have suggested that fusion is initiated by tethering, which leads to formation of a trans-SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) protein complex and then release of lumenal Ca2+, followed by membrane bilayer fusion. We have shown that the R-SNARE (arginine-containing SNARE) protein VAMP (vesicle-associated membrane protein) 7 is necessary for heterotypic fusion between late endosomes and lysosomes, whereas a different R-SNARE, VAMP 8 is required for homotypic fusion of late endosomes. After fusion of lysosomes with late endosomes, lysosomes are re-formed from the resultant hybrid organelles, a process requiring condensation of content and the removal/recycling of some membrane proteins.


2000 ◽  
Vol 352 (1) ◽  
pp. 165-173 ◽  
Author(s):  
Sang Yeul HAN ◽  
Dong Yoon PARK ◽  
Sang Dai PARK ◽  
Seung Hwan HONG

In this study we show the interaction of N-ethylmaleimide-sensitive fusion protein (NSF) with a small GTP-binding protein, Rab6. NSF is an ATPase involved in the vesicular transport within eukaryotic cells. Using the yeast two-hybrid system, we have isolated new NSF-binding proteins from the rat lung cDNA library. One of them was Rab6, which is involved in the vesicular transport within the Golgi and trans-Golgi network as a Ras-like GTPase. We demonstrated that the N-terminal domain of NSF interacted with the C-terminal domain of Rab6, and these proteins were co-immunoprecipitated from the rat brain extract. This interaction was maintained preferentially in the presence of hydrolysable ATP. Recombinant NSF-His6 can also bind to C-terminal Rab6–glutathione S-transferase under the conditions to allow the ATP hydrolysis. Surprisingly, Rab6 stimulates the ATPase activity of NSF by approx. 2-fold as does α-soluble NSF attachment protein receptor. Anti-Rab6 polyclonal antibodies significantly inhibited the Rab6-stimulated ATPase activity of NSF. Furthermore, we found that Rab3 and Rab4 can also associate with NSF and stimulate its ATPase activity. Taken together, we propose a model in which Rab can form an ATP hydrolysis-regulated complex with NSF, and function as a signalling molecule to deliver the signal of vesicle fusion through the interaction with NSF.


2012 ◽  
Vol 92 (4) ◽  
pp. 1915-1964 ◽  
Author(s):  
Haruo Kasai ◽  
Noriko Takahashi ◽  
Hiroshi Tokumaru

The dynamics of exocytosis are diverse and have been optimized for the functions of synapses and a wide variety of cell types. For example, the kinetics of exocytosis varies by more than five orders of magnitude between ultrafast exocytosis in synaptic vesicles and slow exocytosis in large dense-core vesicles. However, in all cases, exocytosis is mediated by the same fundamental mechanism, i.e., the assembly of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. It is often assumed that vesicles need to be docked at the plasma membrane and SNARE proteins must be preassembled before exocytosis is triggered. However, this model cannot account for the dynamics of exocytosis recently reported in synapses and other cells. For example, vesicles undergo exocytosis without prestimulus docking during tonic exocytosis of synaptic vesicles in the active zone. In addition, epithelial and hematopoietic cells utilize cAMP and kinases to trigger slow exocytosis of nondocked vesicles. In this review, we summarize the manner in which the diversity of exocytosis reflects the initial configurations of SNARE assembly, including trans-SNARE, binary-SNARE, unitary-SNARE, and cis-SNARE configurations. The initial SNARE configurations depend on the particular SNARE subtype (syntaxin, SNAP25, or VAMP), priming proteins (Munc18, Munc13, CAPS, complexin, or snapin), triggering proteins (synaptotagmins, Doc2, and various protein kinases), and the submembraneous cytomatrix, and they are the key to determining the kinetics of subsequent exocytosis. These distinct initial configurations will help us clarify the common SNARE assembly processes underlying exocytosis and membrane trafficking in eukaryotic cells.


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