Lucifer Yellow CH modifies voltage-gated channels and a ligand-gated channel in a light-dependent manner

2006 ◽  
Vol 1291 ◽  
pp. 77-80
Author(s):  
Keita Takeuchi ◽  
Kiyonori Yoshii
Keyword(s):  
Lucifer Yellow ◽  
Dependent Manner ◽  
Voltage Gated ◽  
Lucifer Yellow Ch ◽  
Gated Channel ◽  
Voltage Gated Channels

scholarly journals Lucifer Yellow Slows Voltage‐Gated Na + Current Inactivation in a Light‐Dependent Manner in Mice

2003 ◽  
Vol 550 (1) ◽  
pp. 159-167 ◽  
Author(s):  
Yoko Higure ◽  
Yoshimi Katayama ◽  
Keita Takeuchi ◽  
Yoshitaka Ohtubo ◽  
Kiyonori Yoshii
Keyword(s):  
Lucifer Yellow ◽  
Dependent Manner ◽  
Na Current ◽  
Voltage Gated

Prediction of Ion Channels and their Types from Protein Sequences: Comprehensive Review and Comparative Assessment

2019 ◽  
Vol 20 (5) ◽  
pp. 579-592 ◽  
Author(s):  
Jianzhao Gao ◽  
Zhen Miao ◽  
Zhaopeng Zhang ◽  
Hong Wei ◽  
Lukasz Kurgan
Keyword(s):  
Ion Channels ◽  
Empirical Analysis ◽  
Protein Sequences ◽  
Voltage Gated ◽  
New Methods ◽  
Predictive Quality ◽  
Label Prediction ◽  
Gated Channel ◽  
Comprehensive Survey ◽  
Voltage Gated Channels

Background: Ion channels are a large and growing protein family. Many of them are associated with diseases, and consequently, they are targets for over 700 drugs. Discovery of new ion channels is facilitated with computational methods that predict ion channels and their types from protein sequences. However, these methods were never comprehensively compared and evaluated. </P><P> Objective: We offer first-of-its-kind comprehensive survey of the sequence-based predictors of ion channels. We describe eight predictors that include five methods that predict ion channels, their types, and four classes of the voltage-gated channels. We also develop and use a new benchmark dataset to perform comparative empirical analysis of the three currently available predictors. </P><P> Results: While several methods that rely on different designs were published, only a few of them are currently available and offer a broad scope of predictions. Support and availability after publication should be required when new methods are considered for publication. Empirical analysis shows strong performance for the prediction of ion channels and modest performance for the prediction of ion channel types and voltage-gated channel classes. We identify a substantial weakness of current methods that cannot accurately predict ion channels that are categorized into multiple classes/types. </P><P> Conclusion: Several predictors of ion channels are available to the end users. They offer practical levels of predictive quality. Methods that rely on a larger and more diverse set of predictive inputs (such as PSIONplus) are more accurate. New tools that address multi-label prediction of ion channels should be developed.

scholarly journals 3′,5′-Cyclic Adenosine Monophosphate Augments Intracellular Ca2+ Concentration and Gonadotropin-Releasing Hormone (GnRH) Release in Immortalized GnRH Neurons in an Na+-Dependent Manner

Endocrinology ◽  
2002 ◽  
Vol 143 (11) ◽  
pp. 4210-4217 ◽  
Author(s):  
Keisuke Kaneishi ◽  
Yasuo Sakuma ◽  
Hisae Kobayashi ◽  
Masakatsu Kato
Keyword(s):  
Channel Blocker ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Dependent Manner ◽  
Ion Imaging ◽  
Voltage Gated ◽  
Na Permeability ◽  
Camp Assay ◽  
Gnrh Release ◽  
Gated Channel

Abstract In GT1-7 cells, cAMP increases the intracellular Ca2+ concentration ([Ca2+]i) through activation of the voltage-gated Ca2+ channels, thereby facilitating GnRH release. To activate these channels, the membrane potential must be depolarized. In the present study we hypothesize that cAMP depolarizes the cells by increasing the membrane Na+ permeability, as in the case of somatotrophs and pancreatic β-cells. To examine this, we analyzed [Ca2+]i and [Na+]i in GT1-7 cells by an intracellular ion-imaging technique along with cAMP assay by RIA. Forskolin, a direct activator of adenylyl cyclase, increased [Ca2+]i and [Na+]i via cAMP formation. The forskolin-induced increase in [Ca2+]i depended on the presence of Ca2+ and Na+ in the extracellular solution. This response was blocked by the voltage-gated Ca2+ channel blocker, nifedipine; the nonselective cation channel blocker, gadolinium (Gd3+); and the cyclic nucleotide-gated channel blocker, l-cis-diltiazem. In contrast, the forskolin-induced increase in [Na+]i depended only on extracellular Na+, not on Ca2+. Gd3+ and l-cis-diltiazem also blocked the increase in [Na+]i. Furthermore, the forskolin-induced increase in GnRH release was blunted in both low Ca2+ and low Na+ media. The results indicate that cAMP increases the membrane Na+ permeability, probably through nonselective cation channels on GT1-7 cells, thereby promoting GnRH release.

scholarly journals Changes in Local S4 Environment Provide a Voltage-sensing Mechanism for Mammalian Hyperpolarization–activated HCN Channels

2003 ◽  
Vol 123 (1) ◽  
pp. 5-20 ◽  
Author(s):  
Damian C. Bell ◽  
Huan Yao ◽  
Renee C. Saenger ◽  
John H. Riley ◽  
Steven A. Siegelbaum
Keyword(s):  
Hcn Channels ◽  
Transmembrane Segment ◽  
Voltage Sensing ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Pacemaker Channels ◽  
Gated Channel ◽  
Voltage Gated Channels ◽  
S4 Segment ◽  
Positively Charged

The positively charged S4 transmembrane segment of voltage-gated channels is thought to function as the voltage sensor by moving charge through the membrane electric field in response to depolarization. Here we studied S4 movements in the mammalian HCN pacemaker channels. Unlike most voltage-gated channel family members that are activated by depolarization, HCN channels are activated by hyperpolarization. We determined the reactivity of the charged sulfhydryl-modifying reagent, MTSET, with substituted cysteine (Cys) residues along the HCN1 S4 segment. Using an HCN1 channel engineered to be MTS resistant except for the chosen S4 Cys substitution, we determined the reactivity of 12 S4 residues to external or internal MTSET application in either the closed or open state of the channel. Cys substitutions in the NH2-terminal half of S4 only reacted with external MTSET; the rates of reactivity were rapid, regardless of whether the channel was open or closed. In contrast, Cys substitutions in the COOH-terminal half of S4 selectively reacted with internal MTSET when the channel was open. In the open state, the boundary between externally and internally accessible residues was remarkably narrow (∼3 residues). This suggests that S4 lies in a water-filled gating canal with a very narrow barrier between the external and internal solutions, similar to depolarization-gated channels. However, the pattern of reactivity is incompatible with either classical gating models, which postulate a large translational or rotational movement of S4 within a gating canal, or with a recent model in which S4 forms a peripheral voltage-sensing paddle (with S3b) that moves within the lipid bilayer (the KvAP model). Rather, we suggest that voltage sensing is due to a rearrangement in transmembrane segments surrounding S4, leading to a collapse of an internal gating canal upon channel closure that alters the shape of the membrane field around a relatively static S4 segment.

scholarly journals A novel single-domain Na+-selective voltage-gated channel in photosynthetic eukaryotes

2020 ◽  
Author(s):  
Katherine E. Helliwell ◽  
Abdul Chrachri ◽  
Julie Koester ◽  
Susan Wharam ◽  
Alison R. Taylor ◽  
...  
Keyword(s):  
Single Domain ◽  
Inactivation Kinetics ◽  
Control Mechanisms ◽  
Electrical Excitability ◽  
Voltage Gated ◽  
Photosynthetic Eukaryotes ◽  
Voltage Dependent ◽  
Gated Channel ◽  
Voltage Gated Channels ◽  
Short Time

AbstractThe evolution of Na+-selective four-domain voltage-gated channels (4D-Navs) in animals allowed rapid Na+-dependent electrical excitability, and enabled the development of sophisticated systems for rapid and long-range signalling. Whilst bacteria encode single-domain Na+-selective voltage-gated channels (BacNav), they typically exhibit much slower kinetics than 4D-Navs, and are not thought to have crossed the prokaryote-eukaryote boundary. As such, the capacity for rapid Na+-selective signalling is considered to be confined to certain animal taxa, and absent from photosynthetic eukaryotes. Certainly, in land plants, such as the Venus Flytrap where fast electrical excitability has been described, this is most likely based on fast anion channels. Here, we report a unique class of eukaryotic Na+-selective single-domain channels (EukCatBs) that are present primarily in haptophyte algae, including the ecologically important calcifying coccolithophores. The EukCatB channels exhibit very rapid voltage-dependent activation and inactivation kinetics, and sensitivity to the highly selective 4D-Nav blocker tetrodotoxin. The results demonstrate that the capacity for rapid Na+-based signalling in eukaryotes is not restricted to animals or to the presence of 4D-Navs. The EukCatB channels therefore represent an independent evolution of fast Na+-based electrical signalling in eukaryotes that likely contribute to sophisticated cellular control mechanisms operating on very short time scales in unicellular algae.One Sentence SummaryThe capacity for rapid Na+-based signalling has evolved in ecologically important coccolithophore species via a novel class of voltage-gated Na+ channels, EukCatBs.

scholarly journals Direct visualization of redistribution and capping of fluorescent gangliosides on lymphocytes.

1984 ◽  
Vol 99 (5) ◽  
pp. 1575-1581 ◽  
Author(s):  
S Spiegel ◽  
S Kassis ◽  
M Wilchek ◽  
P H Fishman
Keyword(s):  
Cholera Toxin ◽  
Lucifer Yellow ◽  
Protein A ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Ganglioside Gm3 ◽  
Lucifer Yellow Ch ◽  
Toxin Receptor ◽  
Derivatives Of ◽  
Fluorescent Derivatives

Fluorescent derivatives of gangliosides were prepared by oxidizing the sialyl residues to aldehydes and reacting them with fluorescent hydrazides. When rhodaminyl gangliosides were incubated with lymphocytes, the cells incorporated them in a time- and temperature-dependent manner. Initially, the gangliosides were evenly distributed on the cell surface but were redistributed into patches and caps by antirhodamine antibodies. When the cells were then stained with a second antibody or protein A labeled with fluorescein, the fluorescein stain revealed the coincident movement of both the gangliosides and the antirhodamine antibodies. When the cells were treated with both rhodamine and Lucifer yellow CH-labeled gangliosides, the antirhodamine antibodies induced patching and capping of both fluorescent gangliosides but had no effect on cells incubated only with Lucifer yellow CH-labeled gangliosides. In addition, capping was observed on cells exposed to cholera toxin, antitoxin antibodies, and rhodamine-labeled protein A, indirectly showing the redistribution of endogenous ganglioside GM1, the cholera toxin receptor. By incorporating Lucifer yellow CH-labeled GM1 into the cells and inducing capping as above, we were able to demonstrate directly the coordinate redistribution of the fluorescent GM1 and the toxin. When the lymphocytes were stained first with Lucifer yellow CH-labeled exogenous ganglioside GM3, which is not a toxin receptor, there was co-capping of endogenous GM1 (rhodamine) and exogenous GM3 (Lucifer yellow CH). These results suggest that gangliosides may self-associate in the plasma membrane which may explain the basis for ganglioside redistribution and capping.

scholarly journals Hysteretic Behavior in Voltage-Gated Channels

2020 ◽  
Vol 11 ◽  
Author(s):  
Carlos A. Villalba-Galea ◽  
Alvin T. Chiem
Keyword(s):  
Ion Channels ◽  
Hysteretic Behavior ◽  
Channel Activity ◽  
Apparent Contradiction ◽  
Molecular Systems ◽  
Voltage Gated ◽  
Hysteretic Systems ◽  
Gated Channel ◽  
Voltage Gated Channels ◽  
Voltage Gated Ion Channels

An ever-growing body of evidence has shown that voltage-gated ion channels are likely molecular systems that display hysteresis in their activity. This phenomenon manifests in the form of dynamic changes in both their voltage dependence of activity and their deactivation kinetics. The goal of this review is to provide a clear definition of hysteresis in terms of the behavior of voltage-gated channels. This review will discuss the basic behavior of voltage-gated channel activity and how they make these proteins into systems displaying hysteresis. It will also provide a perspective on putative mechanisms underlying hysteresis and explain its potential physiological relevance. It is uncertain whether all channels display hysteresis in their behavior. However, the suggested notion that ion channels are hysteretic systems directly collides with the well-accepted notion that ion channel activity is stochastic. This is because hysteretic systems are regarded to have “memory” of previous events while stochastic processes are regarded as “memoryless.” This review will address this apparent contradiction, providing arguments for the existence of processes that can be simultaneously hysteretic and stochastic.

Ochratoxin A challenges the intestinal epithelial cell integrity: results obtained in model experiments with Caco-2 cells

2019 ◽  
Vol 12 (4) ◽  
pp. 399-407 ◽  
Author(s):  
A. Alizadeh ◽  
P. Akbari ◽  
S. Varasteh ◽  
S. Braber ◽  
H. Malekinejad ◽  
...  
Keyword(s):  
Cell Viability ◽  
Ochratoxin A ◽  
Lucifer Yellow ◽  
Intestinal Barrier ◽  
Clinical Importance ◽  
Hazardous Substances ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Cell Integrity ◽  
Barrier Integrity

Contamination of human and animal diets with different mycotoxins have gained significant attention over the past decade. The intestinal barrier is the first site of exposure and a primary target for nutritional contaminants and hazardous substances including mycotoxins. In this study, the potential impact of ochratoxin A (OTA) on intestinal barrier integrity was highlighted using a human intestinal Caco-2 cell line. Cell viability following OTA exposure was determined by lactate dehydrogenase release and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, markers of barrier integrity, such as transepithelial electrical resistance (TEER) as well as the permeability of Lucifer Yellow (LY) and fluorescein isothiocyanate (FITC)-dextran, were assessed. Furthermore, the protein expression of different tight junction (TJ) proteins, as main constituents of barrier integrity, was evaluated by Western blot. Results show that OTA reduces TEER values in a concentration- and time-dependent manner and increase the permeability of LY through the intestinal epithelial layer, while the cell viability did not change significantly. However, the damage was not severe enough to change the permeability to larger molecules, such as FITC-dextran. OTA exposure down-regulated the expression of TJ proteins claudin-1, -3 and -4 and up-regulated the expression of zona occludens 1. The observation that OTA can disrupt the epithelial barrier is of clinical importance as it may lead to an increased passage of luminal antigens into the systemic circulation.

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