scholarly journals Snarepins Are Functionally Resistant to Disruption by Nsf and αSNAP

2000 ◽  
Vol 149 (5) ◽  
pp. 1063-1072 ◽  
Author(s):  
Thomas Weber ◽  
Francesco Parlati ◽  
James A. McNew ◽  
Robert J. Johnston ◽  
Benedikt Westermann ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Snare Proteins ◽  
Attachment Protein ◽  
Receptor Proteins ◽  
Protein Receptor ◽  
The Face ◽  
Target Membrane ◽  
The Moment ◽  
Protein Attachment ◽  
Lines Of Evidence

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.

scholarly journals The yeast Batten disease orthologue Btn1 controls endosome–Golgi retrograde transport via SNARE assembly

2011 ◽  
Vol 195 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Rachel Kama ◽  
Vydehi Kanneganti ◽  
Christian Ungermann ◽  
Jeffrey E. Gerst
Keyword(s):  
Disease Gene ◽  
Transmembrane Domain ◽  
Batten Disease ◽  
Retrograde Transport ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Late Endosomes ◽  
Target Membrane ◽  
Opposing Effects ◽  
Protein Attachment

The human Batten disease gene CLN3 and yeast orthologue BTN1 encode proteins of unclear function. We show that the loss of BTN1 phenocopies that of BTN2, which encodes a retromer accessory protein involved in the retrieval of specific cargo from late endosomes (LEs) to the Golgi. However, Btn1 localizes to Golgi and regulates soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor (SNARE) function to control retrograde transport. Specifically, BTN1 overexpression and deletion have opposing effects on phosphorylation of the Sed5 target membrane SNARE, on Golgi SNARE assembly, and on Golgi integrity. Although Btn1 does not interact physically with SNAREs, it regulates Sed5 phosphorylation by modulating Yck3, a palmitoylated endosomal kinase. This may involve modification of the Yck3 lipid anchor, as substitution with a transmembrane domain suppresses the deletion of BTN1 and restores trafficking. Correspondingly, deletion of YCK3 mimics that of BTN1 or BTN2 with respect to LE–Golgi retrieval. Thus, Btn1 controls retrograde sorting by regulating SNARE phosphorylation and assembly, a process that may be adversely affected in Batten Disease patients.

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
Keyword(s):  
Fusion Protein ◽  
Intracellular Trafficking ◽  
Neuroendocrine Cells ◽  
Snare Proteins ◽  
Receptor Protein ◽  
Attachment Protein ◽  
Rich Region ◽  
Protein Receptor ◽  
And Function ◽  
Protein Attachment

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.

scholarly journals Modulation of Kv2.1 channel gating and TEA sensitivity by distinct domains of SNAP-25

2006 ◽  
Vol 396 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Yan He ◽  
Youhou Kang ◽  
Yuk-Man Leung ◽  
Fuzhen Xia ◽  
Xiaodong Gao ◽  
...  
Keyword(s):  
Hormone Secretion ◽  
Channel Gating ◽  
Receptor Proteins ◽  
Cell Excitability ◽  
Voltage Gated ◽  
Channel Inactivation ◽  
Protein Receptor ◽  
Outer Pore ◽  
Pore Domain ◽  
Protein Attachment

Distinct domains within the SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) proteins, STX1A (syntaxin 1A) and SNAP-25 (synaptosome-associated protein-25 kDa), regulate hormone secretion by their actions on the cell's exocytotic machinery, as well as voltage-gated Ca2+ and K+ channels. We examined the action of distinct domains within SNAP-25 on Kv2.1 (voltage gated K+ 2.1) channel gating. Dialysis of N-terminal SNAP-25 domains, S197 (SNAP-251–197) and S180 (SNAP-251–180), but not S206 (full-length SNAP-251–206) increased the rate of Kv2.1 channel activation and slowed channel inactivation. Remarkably, these N-terminal SNAP-25 domains, acting on the Kv2.1 cytoplasmic N-terminus, potentiated the external TEA (tetraethylammonium)-mediated block of Kv2.1. To further examine whether these are effects of the channel pore domain, internal K+ was replaced with Na+ and external K+ was decreased from 4 to 1 mM, which decreased the IC50 of the TEA block from 6.8±0.9 mM to >100 mM. Under these conditions S180 completely restored TEA sensitivity (7.9±1.5 mM). SNAP-25 C-terminal domains, SNAP-25198–206 and SNAP-25181–197, had no effect on Kv2.1 gating kinetics. We conclude that different domains within SNAP-25 can form distinct complexes with Kv2.1 to execute a fine allosteric regulation of channel gating and the architecture of the outer pore structure in order to modulate cell excitability.

Distinct Initial SNARE Configurations Underlying the Diversity of Exocytosis

2012 ◽  
Vol 92 (4) ◽  
pp. 1915-1964 ◽  
Author(s):  
Haruo Kasai ◽  
Noriko Takahashi ◽  
Hiroshi Tokumaru
Keyword(s):  
Membrane Trafficking ◽  
Synaptic Vesicles ◽  
Cell Types ◽  
Snare Proteins ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Large Dense Core Vesicles ◽  
Sensitive Factor ◽  
The Common ◽  
Kinetics Of

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.

scholarly journals Comparative analysis of tandem C2 domains from the mammalian synaptotagmin family

2004 ◽  
Vol 378 (2) ◽  
pp. 681-686 ◽  
Author(s):  
Colin RICKMAN ◽  
Molly CRAXTON ◽  
Shona OSBORNE ◽  
Bazbek DAVLETOV
Keyword(s):  
Membrane Trafficking ◽  
Sequence Similarity ◽  
Attachment Protein ◽  
C2 Domains ◽  
Phospholipid Binding ◽  
Calcium Dependent ◽  
Functional Studies ◽  
Protein Receptor ◽  
High Degree ◽  
Protein Attachment

Intracellular membrane traffic is governed by a conserved set of proteins, including Syts (synaptotagmins). The mammalian Syt family includes 15 isoforms. Syts are membrane proteins that possess tandem C2 domains (C2AB) implicated in calcium-dependent phospholipid binding. We performed a pair-wise amino acid sequence comparison, together with functional studies of rat Syt C2ABs, to examine common and divergent properties within the mammalian family. Sequence analysis indicates three different C2AB classes, the members of which share a high degree of sequence similarity. All the other C2ABs are highly divergent in sequence. Nearly half of the Syt family does not exhibit calcium/phospholipid binding in comparison to Syt I, the major brain isoform. Syts do, however, possess a more conserved function, namely calcium-independent binding to target SNARE (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) heterodimers. All tested isoforms, except Syt XII and Syt XIII, bound the target SNARE heterodimer comprising syntaxin 1 and SNAP-25 (25 kDa synaptosome-associated protein). Our present study suggests that many Syt isoforms can function in membrane trafficking to interact with the target SNARE heterodimer on the pathway to calcium-triggered membrane fusion.

scholarly journals Endosomal and Phagosomal SNAREs

2018 ◽  
Vol 98 (3) ◽  
pp. 1465-1492 ◽  
Author(s):  
Ilse Dingjan ◽  
Peter T. A. Linders ◽  
Danielle R. J. Verboogen ◽  
Natalia H. Revelo ◽  
Martin ter Beest ◽  
...  
Keyword(s):  
Intracellular Transport ◽  
Snare Proteins ◽  
Intracellular Pathogens ◽  
Snare Protein ◽  
Attachment Protein ◽  
System A ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Organelle Communication ◽  
Factor Attachment Protein Receptor

The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein family is of vital importance for organelle communication. The complexing of cognate SNARE members present in both the donor and target organellar membranes drives the membrane fusion required for intracellular transport. In the endocytic route, SNARE proteins mediate trafficking between endosomes and phagosomes with other endosomes, lysosomes, the Golgi apparatus, the plasma membrane, and the endoplasmic reticulum. The goal of this review is to provide an overview of the SNAREs involved in endosomal and phagosomal trafficking. Of the 38 SNAREs present in humans, 30 have been identified at endosomes and/or phagosomes. Many of these SNAREs are targeted by viruses and intracellular pathogens, which thereby reroute intracellular transport for gaining access to nutrients, preventing their degradation, and avoiding their detection by the immune system. A fascinating picture is emerging of a complex transport network with multiple SNAREs being involved in consecutive trafficking routes.

The molecular mechanisms of the mammalian exocyst complex in exocytosis

2006 ◽  
Vol 34 (5) ◽  
pp. 687-690 ◽  
Author(s):  
S. Wang ◽  
S.C. Hsu
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Secretory Vesicles ◽  
Attachment Protein ◽  
Trafficking Pathway ◽  
Exocyst Complex ◽  
Protein Receptor ◽  
Associated Proteins ◽  
Protein Attachment

Exocytosis is a highly ordered vesicle trafficking pathway that targets proteins to the plasma membrane for membrane addition or secretion. Research over the years has discovered many proteins that participate at various stages in the mammalian exocytotic pathway. At the early stage of exocytosis, co-atomer proteins and their respective adaptors and GTPases have been shown to play a role in the sorting and incorporation of proteins into secretory vesicles. At the final stage of exocytosis, SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) and SNARE-associated proteins are believed to mediate the fusion of secretory vesicles at the plasma membrane. There are multiple events that may occur between the budding of secretory vesicles from the Golgi and the fusion of these vesicles at the plasma membrane. The most obvious and best-known event is the transport of secretory vesicles from Golgi to the vicinity of the plasma membrane via microtubules and their associated motors. At the vicinity of the plasma membrane, however, it is not clear how vesicles finally dock and fuse with the plasma membrane. Identification of proteins involved in these events should provide important insights into the mechanisms of this little known stage of the exocytotic pathway. Currently, a protein complex, known as the sec6/8 or the exocyst complex, has been implicated to play a role at this late stage of exocytosis.

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