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.

scholarly journals Exploring Kv1.2 Channel Inactivation Through MD Simulations and Network Analysis

2021 ◽  
Vol 8 ◽  
Author(s):  
Flavio Costa ◽  
Carlo Guardiani ◽  
Alberto Giacomello
Keyword(s):  
Molecular Basis ◽  
Md Simulations ◽  
Childhood Epilepsy ◽  
Contact Map ◽  
Voltage Gated ◽  
Channel Inactivation ◽  
Inactivation Mechanism ◽  
Combined Simulation ◽  
Pore Domain ◽  
Voltage Sensor Domain

The KCNA2 gene encodes the Kv1.2 channel, a mammalian Shaker-like voltage-gated K+ channel, whose defections are linked to neuronal deficiency and childhood epilepsy. Despite the important role in the kinetic behavior of the channel, the inactivation remained hereby elusive. Here, we studied the Kv1.2 inactivation via a combined simulation/network theoretical approach that revealed two distinct pathways coupling the Voltage Sensor Domain and the Pore Domain to the Selectivity Filter. Additionally, we mutated some residues implicated in these paths and we explained microscopically their function in the inactivation mechanism by computing a contact map. Interestingly, some pathological residues shown to impair the inactivation lay on the paths. In summary, the presented results suggest two pathways as the possible molecular basis of the inactivation mechanism in the Kv1.2 channel. These pathways are consistent with earlier mutational studies and known mutations involved in neuronal channelopathies.

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.

SNAP-24, a Drosophila SNAP-25 homologue on granule membranes, is a putative mediator of secretion and granule-granule fusion in salivary glands

2000 ◽  
Vol 113 (22) ◽  
pp. 4055-4064 ◽  
Author(s):  
B.A. Niemeyer ◽  
T.L. Schwarz
Keyword(s):  
Plasma Membrane ◽  
Salivary Glands ◽  
Receptor Proteins ◽  
Protein Receptor ◽  
Compound Exocytosis ◽  
Glue Secretion ◽  
Protein Attachment ◽  
Identification And Characterization

Fusion of vesicles with target membranes is dependent on the interaction of target (t) and vesicle (v) SNARE (soluble NSF (N-ethylmaleimide-sensitive fusion protein) attachment protein receptor) proteins located on opposing membranes. For fusion at the plasma membrane, the t-SNARE SNAP-25 is essential. In Drosophila, the only known SNAP-25 isoform is specific to neuronal axons and synapses and additional t-SNAREs must exist that mediate both non-synaptic fusion in neurons and constitutive and regulated fusion in other cells. Here we report the identification and characterization of SNAP-24, a closely related Drosophila SNAP-25 homologue, that is expressed throughout development. The spatial distribution of SNAP-24 in the nervous system is punctate and, unlike SNAP-25, is not concentrated in synaptic regions. In vitro studies, however, show that SNAP-24 can form core complexes with syntaxin and both synaptic and non-synaptic v-SNAREs. High levels of SNAP-24 are found in larval salivary glands, where SNAP-24 localizes mainly to granule membranes rather than the plasma membrane. During glue secretion, the massive exocytotic event of these glands, SNAP-24 containing granules fuse with one another and the apical membrane, suggesting that glue secretion utilizes compound exocytosis and that SNAP-24 mediates secretion.

scholarly journals Outer Pore Domain of TRPV1 Ion Channel is Required for Temperature-Independent Step During Temperature-Activation

2010 ◽  
Vol 98 (3) ◽  
pp. 227a
Author(s):  
Jorg Grandl ◽  
Sung Eun Kim ◽  
Valerie Uzzell ◽  
Badry Bursulaya ◽  
Matt Petrus ◽  
...  
Keyword(s):  
Ion Channel ◽  
Outer Pore ◽  
Temperature Activation ◽  
Pore Domain

scholarly journals Proton Sensors in the Pore Domain of the Cardiac Voltage-gated Sodium Channel

2013 ◽  
Vol 288 (7) ◽  
pp. 4782-4791 ◽  
Author(s):  
David K. Jones ◽  
Colin H. Peters ◽  
Charlene R. Allard ◽  
Tom W. Claydon ◽  
Peter C. Ruben
Keyword(s):  
Sodium Channel ◽  
Voltage Gated Sodium Channel ◽  
Voltage Gated ◽  
Pore Domain

S-nitrosylation of syntaxin 1 at Cys145 is a regulatory switch controlling Munc18-1 binding

2008 ◽  
Vol 413 (3) ◽  
pp. 479-491 ◽  
Author(s):  
Zoë J. Palmer ◽  
Rory R. Duncan ◽  
James R. Johnson ◽  
Lu-Yun Lian ◽  
Luciane V. Mello ◽  
...  
Keyword(s):  
Release Kinetics ◽  
Cell Types ◽  
Snare Complex ◽  
Syntaxin 1A ◽  
Dynamic Simulations ◽  
Closed Conformation ◽  
Quantal Size ◽  
Protein Receptor ◽  
Protein Attachment

Exocytosis is regulated by NO in many cell types, including neurons. In the present study we show that syntaxin 1a is a substrate for S-nitrosylation and that NO disrupts the binding of Munc18-1 to the closed conformation of syntaxin 1a in vitro. In contrast, NO does not inhibit SNARE {SNAP [soluble NSF (N-ethylmaleimide-sensitive fusion protein) attachment protein] receptor} complex formation or binding of Munc18-1 to the SNARE complex. Cys145 of syntaxin 1a is the target of NO, as a non-nitrosylatable C145S mutant is resistant to NO and novel nitrosomimetic Cys145 mutants mimic the effect of NO on Munc18-1 binding in vitro. Furthermore, expression of nitrosomimetic syntaxin 1a in living cells affects Munc18-1 localization and alters exocytosis release kinetics and quantal size. Molecular dynamic simulations suggest that NO regulates the syntaxin–Munc18 interaction by local rearrangement of the syntaxin linker and H3c regions. Thus S-nitrosylation of Cys145 may be a molecular switch to disrupt Munc18-1 binding to the closed conformation of syntaxin 1a, thereby facilitating its engagement with the membrane fusion machinery.

Structure of the human voltage-gated sodium channel Nav1.4 in complex with β1

Science ◽  
2018 ◽  
Vol 362 (6412) ◽  
pp. eaau2486 ◽  
Author(s):  
Xiaojing Pan ◽  
Zhangqiang Li ◽  
Qiang Zhou ◽  
Huaizong Shen ◽  
Kun Wu ◽  
...  
Keyword(s):  
Model Building ◽  
Fast Inactivation ◽  
Potential Generation ◽  
Voltage Gated ◽  
Cryo Electron Microscopy ◽  
Disease Mutations ◽  
Mechanistic Investigation ◽  
Pore Domain ◽  
Blocking Mechanism ◽  
Insight Into

Voltage-gated sodium (Nav) channels, which are responsible for action potential generation, are implicated in many human diseases. Despite decades of rigorous characterization, the lack of a structure of any human Nav channel has hampered mechanistic understanding. Here, we report the cryo–electron microscopy structure of the human Nav1.4-β1 complex at 3.2-Å resolution. Accurate model building was made for the pore domain, the voltage-sensing domains, and the β1 subunit, providing insight into the molecular basis for Na+ permeation and kinetic asymmetry of the four repeats. Structural analysis of reported functional residues and disease mutations corroborates an allosteric blocking mechanism for fast inactivation of Nav channels. The structure provides a path toward mechanistic investigation of Nav channels and drug discovery for Nav channelopathies.

scholarly journals Properties of the Voltage-Gated Proton Channel Gating Currents

2018 ◽  
Vol 114 (3) ◽  
pp. 546a ◽  
Author(s):  
Emerson M. Carmona ◽  
David Baez-Nieto ◽  
Amaury Pupo ◽  
Karen Castillo ◽  
Osvaldo Alvarez ◽  
...  
Keyword(s):  
Channel Gating ◽  
Proton Channel ◽  
Gating Currents ◽  
Voltage Gated
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