The intracellular N-terminus domain of the acid-sensing ion channel 1a participates in channel opening and membrane expression

2021 ◽  
pp. MOLPHARM-AR-2020-000153
Author(s):  
Wen Li ◽  
Xiaomu Wang ◽  
Xiandong Meng ◽  
Dong Wei
Keyword(s):  
Ion Channel ◽  
Membrane Expression ◽  
Channel Opening ◽  
N Terminus

Tyrosine-protein kinase Src regulates Kv1.5 channel activity and membrane expression through interaction with the N-terminus of the channel

2020 ◽  
Author(s):  
Taylore Dodd ◽  
Tingzhong Wang ◽  
Shetuan Zhang
Keyword(s):  
Protein Kinase ◽  
Cell Voltage ◽  
Underlying Mechanism ◽  
Delayed Rectifier ◽  
Binding Motif ◽  
Membrane Expression ◽  
Binding Motifs ◽  
Delayed Rectifier Potassium Current ◽  
N Terminus ◽  
Tyrosine Protein Kinase

Kv1.5 is a voltage-gated potassium channel that generates the ultra-rapid delayed rectifier potassium current (IKur) important in the repolarization of the atrial action potential. Malfunction of the Kv1.5 channel often results in atrial fibrillation (AFib). A reduction in Kv1.5 current (IKv1.5) occurs upon activation of the endogenous tyrosine-protein kinase Src. The Src SH3 domain binds to proline-rich motifs located within the N-terminus of Kv1.5. Disruption of these binding motifs has been involved in the development of familial AFib. The mechanism underlying the reduction of IKv1.5 upon Src activation has not yet been established and the relationship between Kv1.5 and Src is poorly understood. Therefore, the present study aims to further elucidate the mechanism behind IKv1.5  reduction. The hypothesis that Src regulates Kv1.5 activity by altering the density of mature membrane-localized channels was tested using whole-cell voltage clamp and Western blot analysis. We demonstrate that Src tonically inhibits Kv1.5 activity and decreases the density of mature membrane-localized channels. Kv1.5 channels possessing mutations within the Src binding motifs were also investigated and it was determined that each binding motif contributes to the Kv1.5-Src relationship, however, the binding of Src to an individual motif is sufficiently effective. Our findings indicate that Src regulates Kv1.5 through an interaction with the N-terminal binding motifs and suggests that the inhibition of forward trafficking may be involved in the underlying mechanism. (Supported by the Heart and Stroke foundation of Canada and The Canadian Institutes of Health Research).

scholarly journals Functional Contributions of Positive Charges in the Pore-Lining Helix 3 of the Bordetella pertussis CyaA-Hemolysin to Hemolytic Activity and Ion-Channel Opening

Toxins ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 109 ◽  
Author(s):  
Chattip Kurehong ◽  
Chalermpol Kanchanawarin ◽  
Busaba Powthongchin ◽  
Panchika Prangkio ◽  
Gerd Katzenmeier ◽  
...  
Keyword(s):  
Ion Channel ◽  
Bordetella Pertussis ◽  
Hemolytic Activity ◽  
Channel Opening ◽  
Pore Lining

scholarly journals Acetylated tubulin is essential for touch sensation in mice

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shane J Morley ◽  
Yanmei Qi ◽  
Loredana Iovino ◽  
Laura Andolfi ◽  
Da Guo ◽  
...  
Keyword(s):  
Ion Channel ◽  
Sensory Neurons ◽  
Mechanical Energy ◽  
Mechanical Stimuli ◽  
Acetylated Tubulin ◽  
Fundamental Level ◽  
Tubulin Acetylation ◽  
Channel Opening ◽  
Mechanosensitive Ion Channel ◽  
Touch Sensation

At its most fundamental level, touch sensation requires the translation of mechanical energy into mechanosensitive ion channel opening, thereby generating electro-chemical signals. Our understanding of this process, especially how the cytoskeleton influences it, remains unknown. Here we demonstrate that mice lacking the α-tubulin acetyltransferase Atat1 in sensory neurons display profound deficits in their ability to detect mechanical stimuli. We show that all cutaneous afferent subtypes, including nociceptors have strongly reduced mechanosensitivity upon Atat1 deletion, and that consequently, mice are largely insensitive to mechanical touch and pain. We establish that this broad loss of mechanosensitivity is dependent upon the acetyltransferase activity of Atat1, which when absent leads to a decrease in cellular elasticity. By mimicking α-tubulin acetylation genetically, we show both cellular rigidity and mechanosensitivity can be restored in Atat1 deficient sensory neurons. Hence, our results indicate that by influencing cellular stiffness, α-tubulin acetylation sets the force required for touch.

scholarly journals Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

2016 ◽  
Vol 113 (43) ◽  
pp. E6696-E6703 ◽  
Author(s):  
Mieke Nys ◽  
Eveline Wijckmans ◽  
Ana Farinha ◽  
Özge Yoluk ◽  
Magnus Andersson ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Ion Channel ◽  
Binding Site ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Channel Pore ◽  
X Ray ◽  
Electrophysiological Recordings ◽  
Channel Opening ◽  
Dynamics Simulations

Pentameric ligand-gated ion channels or Cys-loop receptors are responsible for fast inhibitory or excitatory synaptic transmission. The antipsychotic compound chlorpromazine is a widely used tool to probe the ion channel pore of the nicotinic acetylcholine receptor, which is a prototypical Cys-loop receptor. In this study, we determine the molecular determinants of chlorpromazine binding in the Erwinia ligand-gated ion channel (ELIC). We report the X-ray crystal structures of ELIC in complex with chlorpromazine or its brominated derivative bromopromazine. Unexpectedly, we do not find a chlorpromazine molecule in the channel pore of ELIC, but behind the β8–β9 loop in the extracellular ligand-binding domain. The β8–β9 loop is localized downstream from the neurotransmitter binding site and plays an important role in coupling of ligand binding to channel opening. In combination with electrophysiological recordings from ELIC cysteine mutants and a thiol-reactive derivative of chlorpromazine, we demonstrate that chlorpromazine binding at the β8–β9 loop is responsible for receptor inhibition. We further use molecular-dynamics simulations to support the X-ray data and mutagenesis experiments. Together, these data unveil an allosteric binding site in the extracellular ligand-binding domain of ELIC. Our results extend on previous observations and further substantiate our understanding of a multisite model for allosteric modulation of Cys-loop receptors.

scholarly journals Cytolytic and ion channel-forming properties of the N terminus of lymphocyte perforin.

1991 ◽  
Vol 88 (11) ◽  
pp. 4621-4625 ◽  
Author(s):  
D. M. Ojcius ◽  
P. M. Persechini ◽  
L. M. Zheng ◽  
P. C. Notaroberto ◽  
S. C. Adeodato ◽  
...  
Keyword(s):  
Ion Channel ◽  
N Terminus

scholarly journals Apocalmodulin Itself Promotes Ion Channel Opening and Ca2+ Regulation

Cell ◽  
2014 ◽  
Vol 159 (3) ◽  
pp. 608-622 ◽  
Author(s):  
Paul J. Adams ◽  
Manu Ben-Johny ◽  
Ivy E. Dick ◽  
Takanari Inoue ◽  
David T. Yue
Keyword(s):  
Ion Channel ◽  
Channel Opening

scholarly journals Evidence that ion conduction in 5-HT3A receptors proceeds through lateral portals in the cytosol

2020 ◽  
Author(s):  
Antonia G. Stuebler ◽  
Michaela Jansen
Keyword(s):  
Ion Channel ◽  
Disulfide Bond ◽  
Conformational Changes ◽  
Bond Formation ◽  
Disulfide Bond Formation ◽  
Transmembrane Segment ◽  
Ion Conduction ◽  
Intracellular Domain ◽  
Channel Opening ◽  
Conduction Pathway

AbstractThe intracellular domain of the serotonin type 3A receptor, a pentameric ligand-gated ion channel, is crucial for regulating conductance. However, the specific ion conduction pathway through this domain is less clear. The intracellular domain starts with a short loop after the third transmembrane segment, followed by a short α-helical segment, a large unstructured loop, and finally the membrane-associated MA-helix that continues into the last transmembrane segment. The MA-helices from all five subunits form the extension of the transmembrane ion channel and shape what has been described as a “closed vestibule”, with their lateral portals obstructed by loops and their cytosolic ends forming a tight hydrophobic constriction. The question remains whether the lateral portals or cytosolic constriction conduct ions upon channel opening. In the present study, we used disulfide bond formation between pairs of engineered cysteines to probe the proximity and mobility of segments of the MA-helices most distal to the membrane bilayer. Our results indicate that the proximity and orientation for cysteine pairs at I409C/R410C, in close proximity to the lateral windows, and L402C/L403C, at the cytosolic ends of the MA-helices, are conducive for disulfide bond formation. While conformational changes associated with gating promote crosslinking for I409C/R410C, which in turn decreases channel currents, crosslinking of L402C/L403C is functionally silent in macroscopic currents. These results support the hypothesis that concerted conformational changes open the lateral portals for ion conduction, rendering ion conduction through the vertical portal unlikely.SignificanceThe intracellular domain (ICD) of pentameric ligand-gated ion channels (pLGICs) is the most diverse domain within receptors of the Cys-loop superfamily. Despite being the least understood domain of pLGICs, its impact on ion-channel function and contribution to the cytosolic exit pathway of the channel have been investigated. X-ray and cryo-EM structures have captured the structured segments of the ICD of 5-HT3A receptors in different conformational states with lower resolution of the ICD as compared to the other domains. Here, we provide experimentally derived evidence for the importance of the differential mobility of the cytosolic segment of the MA-helices, which supports the existence of lateral portals as opposed to a vertical pathway for 5-HT3A receptors.

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