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Topic: Ion channel

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In the News (Tue 25 Jun 19)

  Ion Channel, Patch Clamp and Electrophysiology Research   (Site not responding. Last check: 2007-10-30)
Ion channels are transmembrane pores which allow the passage of ions (charged particles) into and out of a cell down the electrochemical gradient.
Other potassium channels include the inwardly rectifying potassium channels which are not voltage-gated, but allow influx of potassium ions upon hyperpolarization which dislodges magnesium from a binding site in the pore.
This superfamily of ion channels is subdivided into the cyclic nucleotide gated channels (CNG) and hyperpolarization-activated cyclic nucleotide gated channels (HCN).
www.ionchannels.org   (1106 words)

  Ligand-Gated Ion Channel Database
Ligand-Gated Ion Channels are transmembrane proteins that can exist under different conformations, at least one forming a pore through the membrane connecting the two neighbour compartments.
The equilibrium between the various conformations is affected by the binding of ligands on the channels.
The ATP gated channels (ATP2x receptors) are made of three homologous subunits, each with two transmembrane segments.
www.ebi.ac.uk /compneur-srv/LGICdb/LGICdb.php   (663 words)

  Ion Channel Glossary
Ions with high conductances are often said to have binding sites in the channel that are relatively high in free energy compared to an ion with lower conductance (which sticks more tightly to binding sites).
Ions are assumed to move independently of one another and the channel properties.
This is equalivant to 6.28 X 10^6 ions per second per applied volt of conductance of cations thru the pore when the concentration of cations is equal on both sides of the membrane.
www2.montana.edu /cftr/ion_channel_glossary.htm   (1991 words)

 IBM Research | Projects | Ion Channels
A key element in a typical ion channel is a bundle of alpha helices transverse to the lipid bilayer.
Ion penetration through the ion channel is through this water column, which enables conservation of the ion's hydration shell in the transport process.
X-ray structures for ion channels are rarely available, because of their difficulty in crystallization, and MD can supply such information given basic input such as the number of helices in the bundle.
www.research.ibm.com /ionchannel   (691 words)

 Ion Channel - Gene Transfer Therapy
Ion Channel Innovations is a development stage biotechnology company formed to develop Ion Channel Therapy (ICT), an innovative gene transfer therapy solution expected to be safe and long-term effective for erectile dysfunction, urinary incontinence, and potentially other smooth muscle diseases.
FDA approves Ion Channel second IND. The indication is for gene transfer of the overactive bladder.
Ion Channel's report of the phase I trials results for gene transfer for the indication of erectile dysfunction was print published in Human Gene Therapy.
www.ionchannelinnovations.com   (239 words)

 Ion Channel Blockade: acyclic (Guarded Receptor) and cyclic (Modulated or Allosteric)
This was because Hondeghem proposed a shift in the "h" curve for inactivation of drug-complexed channels, and such a shift cannot be "identified" because it cannot be separated from a shift caused by voltage dependent blocking.
The interesting feature of blockade of many ion channels is that the fraction of drug-complexed channels depends on the frequency of stimulation.
Blue is the fraction of unblocked channels in the rest state and red, the fraction of inactivated channels.
frank.itlab.us /guarded.html   (4390 words)

 Ion channel structure and function
Ion channels are membrane protein complexes and their function is to facilitate the diffusion of ions across biological membranes.
Ion channels can be classified according to which chemical or physical modulator controls their gating activity.
Channel cross section (electron density map) with positions of the pore lining transmembrane segment M2 (left; solid bars) and helical plot of the amino acid sequence of transmembrane segment M2.
www.whatislife.com /reader/channels/channels.html   (2080 words)

 Ion Channel History Page 2
The word ion comes from the Greek for "wanderer", because, when placed in an electric field, ions are seen to move in accord with the strength and direction of the electric field applied.
They saw "steps" in increased conductance which they interpreted to be increases in ion conductances as the individual ion channels bound to the bilayers one at a time and started letting ions thru.
If this is the case, then one can use the flow of ions in or out of the ion channel to detect the flow of ions as one would detect a current in a wire.
opal.msu.montana.edu /cftr/IonChannelPrimers/ion_channel_history2.htm   (2239 words)

 Icagen - Technology
Ions generally cannot move freely across cell membranes, but must enter or exit a cell through pores created by ion channels.
Ion channels open and close, or gate, in response to particular stimuli, including ions, other cellular factors, changes in electrical voltage or drugs.
Ion channels are also attractive therapeutic targets because they play crucial roles in all functions and pathophysiological processes in the human body.
www.icagen.com /technology/ionchannels.html   (341 words)

 Roderick MacKinnon
Among their many functions, ion channels control the pace of the heart, regulate the secretion of hormones into the bloodstream, and generate the electrical impulses underlying information transfer in the nervous system.
Ion channels, like enzymes, have their specific substrates: potassium, sodium, calcium, and chloride channels permit only their namesake ions to diffuse through their pores.
Ion channel gating refers to opening and closing of the ion conduction pore in response to a specific stimulus.
www.hhmi.org /research/investigators/mackinnon.html   (1132 words)

 [No title]
This channel was already known to play a crucial role in Na+ absorption in the distal part of the kidney tubule and to be the target of aldosterone action.
Thus the ability of shrunk or swollen cells to restore their normal volume by means of activating ion channels and transporters is impaired when normal actin filament turnover is disturbed by drugs such as cytochalasin (49).
A crucial role of ion channels in endothelial Ca2+ signaling is the fine-tuning of the electrochemical gradient for Ca2+ (176, 226, 271, 272).
www.lycos.com /info/ion--ion-channel.html   (833 words)

That is, the interaction between the ions and the channel protein caused the channel to switch between its closed and open states.
This work opened the possibility that some effects, previously attributed only to the changes in conformation of the ion channel protein itself, may actual be due to the dynamical properties of the ions in their interactions with themselves and with the channel protein.
This suggests that the interaction between the channel protein and the ions passing through it could be important in changing the conformational state of the protein, as was suggested by the model of Chinarov et al.
www.ccs.fau.edu /~liebovitch/dyn.html   (9624 words)

 Hydra Biosciences : Programs | Pipeline : Ion Channel Program - Hydra Biosciences, biopharmaceutical company, ...
Ion channels are transmembrane proteins that facilitate the flow of ions (positively and negatively charged molecules) into and out of the cell.
The Transient Receptor Potential (TRP) channel family comprises a novel group of non-selective cation channels that are distinct from classical voltage gated ion channels.
Ion channels have been implicated in many diseases, including hypertension, cardiac arrhythmias, gastrointestinal disorders, cystic fibrosis and pathological pain.
www.hydrabiosciences.com /programs_ion.htm   (572 words)

In sodium and calcium channels, these are covalently linked but the non-covalently linked potassium channel subunits come in a variety of flavours, allowing for different mixes and thus a variety of functional units.
K channels are blocked by a substantial array of drugs, including many "antiarrhythmics" such as Vaughan Williams class III agents, and also class IA and IC drugs.
channels, which is resistant to the effect of 4AP, and sensitive to the presence of calcium ions).
www.anaesthetist.com /icu/organs/heart/ion.htm   (807 words)

 Ion channels
namely, because the distance between the potassium ion and the oxygen atoms of the amino acids of in the filter region is the same as that between the potassium ion and the oxygen atoms in the water molecules surrounding the potassium ion when it is hydrated in aqueous solution outside the filter.
The ability of the channel to strip the potassium ion of its water and allow it to pass at no cost in energy is a kind of selective catalyzed ion transport.
Outside the cell membrane the ions are bound to water molecules with certain distances to the oxygen atoms of the water.
fig.cox.miami.edu /~cmallery/150/memb/ion_channels.htm   (1073 words)

 Los Alamos National Laboratory (LANL): Scientists propose new method for studying ion channel kinetics
An ion channel is a protein pore that lets ions (charged atoms such as calcium) pass through a cell's membrane.
Ion channels gating functions are critical to biological function.
Faulty ion channels in humans have been shown to cause severe diseases like cystic fibrosis and diabetes and more subtle, but still dangerous physiological effects, like over-responses to general anesthetics.
www.lanl.gov /news/index.php/fuseaction/home.story/story_id/6449   (694 words)

 Ion Channel Kinetics
Ion channels are gates in the membrane of neural cells that regulate the concentration of charged elements such as potassium, calcium, or sodium inside and outside the cell membrane.
Thus, biological or pharmacological techniques that affect the kinetics of ion transport across a neural membrane become, in essence, a form of electrical stimulation in that they produce electrical activation—or deactivation—of neurons just as if a stimulating electrode had produced the change in ion channel kinetics.
The activated potassium channels hyperpolarized the cell membrane and decreased neuronal excitability by a factor of 10.
www.neurotechreports.com /pages/ionchannels.html   (822 words)

 Upstate - Drug Discovery Products - Ion Channel
Historically, ion channels have been under exploited as drug targets primarily due to the lack of functional high throughput screening technologies.
The objective is to provide the pharmaceutical industry with a range of ion channel cell lines to support drug discovery, lead optimisation and safety pharmacology functions.
One such ion channel is KvLQT1/minK that along with hERG, is responsible for the repolarizing phase of the action potential.
www.upstate.com /discovery/products/ionchannel.asp   (452 words)

 Targeted Life Science Marketing-Ion Channel Media Group Ltd.   (Site not responding. Last check: 2007-10-30)
Ion Channel Media Group specializes in targeted life science advertising and marketing programs.
Whether your product or service is related to stem cells, apoptosis, ion channels, cloning, or a myriad of other areas, we can deliver the customers you need.
Serious Traffic: Ion Channel Media Group controls many biotechnology web properties.
www.ionchannelmedia.com   (397 words)

 Ion channels: Web focus : Nature
Ion channels allow the movement of ions across cell membranes, and therefore fundamental physiological processes such as muscle contraction.
In 1998, we saw for the first time what an ion channel actually looks like in a paper describing the crystal structure of a potassium channel.
Now we have an array of ion channel structures, which we exemplify in this regularly updated collection of papers that illustrate the structural revolution that the field is currently experiencing.
www.nature.com /nature/focus/ionchannel   (390 words)

 BioMed Central | Full text | Control of ion channel expression for patch clamp recordings using an inducible expression ...
This approach to controlling ion channel expression is relatively simple, greatly enhances the speed and efficiency with which high quality macroscopic current data can be collected, and makes it possible to easily and reliably record single channel currents in a mammalian cell heterologous expression system.
Channel expression levels were then under the control of a competition between constitutively expressed Tet repressor protein and exogenously added tetracycline.
Channel expression was determined using standard whole cell patch clamp recordings, as described previously [9].
www.biomedcentral.com /1471-2202/4/15   (3659 words)

 Protein tags regulate key ion channel
Ion channels are in every cell in the human body.
Ion channels allow ions such as potassium, sodium and calcium to flow in and out and so are key regulators of many fundamental processes in biology.
Goldstein's team discovered the type of ion channel known as background (or leak) potassium channels in yeast cells in 1995 and in fruit flies in 1996.
www.eurekalert.org /pub_releases/2005-04/uocm-ptr040205.php   (791 words)

 Ion channel forming colicins.
The ion-conducting channels are formed by a single monomer, are voltage activated and voltage gated, and conduct ions of the size of a hydrated sodium ion or hydrated potassium ion through channels that are 8Å in diameter, very similar to the channel diameter found in the acetylcholine receptor superfamily for example.
That the channels formed by the fragment can not be related directly to studies of the whole colicin is emphasized by single channel conductance measurements with colicin Ia, and to a lesser degree by studies with colicins A and E1.
The N-terminal helices (helices 1-7) lie on the surface of the membrane with the helical axis being oriented parallel to the membrane plane [16.
www.sinica.edu.tw /~pxig/membrane/Colicin.html   (5160 words)

 Study of Ion Channel Currents in a Circadian Pacemaker
It is known that ion channels, which are specific transmembrane proteins found on the surfaces of many living cells, are involved in the generation and expression of circadian oscillations.
The purpose of this project is to study the behavior of ion channel currents in the circadian pacemaker neurons of Bulla at the single channel level.
This is known as the cell-attached configuration in which single ion channel currents can be detected; the currents through the whole cell could be measured in the configuration where the patch of membrane trapped by the patch pipette tip is ruptured.
www.selu.edu /Academics/ArtsSciences/connections/journal3/beadle/beadle.htm   (1074 words)

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