Voltage-gated ion channel

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Topic: Voltage-gated ion channel

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	Voltage-gated ion channel - Wikipedia, the free encyclopedia
		Examples include the sodium and potassium voltage-gated channels of nerve and muscle, and the voltage-gated calcium channels that play a role in neurotransmitter release in pre-synaptic endings.
		From crystallographic structural studies of a potassium channel, assuming that this structure remains intact in the corresponding plasma membrane, it is possible to surmise that when a potential difference is introduced over the membrane, the associated electromagnetic field induces a conformational change in the potassium channel.
		The conformational change distorts the shape of the channel proteins sufficiently such that the cavity, or channel, opens to admit ion influx or efflux to occur across the membrane, down its electrochemical gradient.
	en.wikipedia.org /wiki/Voltage-gated_ion_channel (256 words)

	CELL PHYSIOLOGY: ON VOLTAGE-GATED ION CHANNELS
		The pore domain is responsible for the ion selectivity and conduction, and also for channel gating per se, whereas the voltage-sensing domain triggers a change in conformation of the pore domain in response to changes in transmembrane voltage.
		Studies of the potassium ion channel have identified two segments that contain several charged protein residues, and these charged residues apparently sense changes in the potential difference across the membrane and form part of the membrane "voltage sensor".
		Sodium channels, which are glycosylated proteins with a relative molecular mass of approximately 300,000, are responsible for signal transduction and amplification, and are chief targets of anesthetic drugs and neurotoxins.
	scienceweek.com /2005/sw050422-3.htm (1887 words)

	Ion Channels for Beginners Page 4
		The three main groups of ion channels are 1) the voltage-gated channels such as the sodium and potassium channels of the nerve axons and nerve terminals, 2) the extracellular ligand-activated channels which includes channels such as GABA and glycine receptor channels, most of which are regulated by ligands that are "neurotransmitters".
		Murine myotonia and hyperekplexia are ion channel diseases caused by insertion of transposons.
		For example, it is possible to arrange ion channels according to the ion that they conduct thru their pores rather then regulation mechanisms, however this method has the problem that very few other characteristics will be shared in common among the channels.
	opal.msu.montana.edu /cftr/IonChannelPrimers/beginners4.htm (9238 words)

	Molecular Properties of Voltage-Gated Ion Channels
		The ion specificity of channel proteins is due mainly to coordination of the selected ion with specific residues in the P segments, thus lowering the activation energy for passage of the selected ion compared with other ions (see Figure 21-25).
		Patch-clamping techniques, which permit measurement of ion movement through single channels, are used to determine the potential at which a channel opens, its ion conductivity, and the rate of channel inactivation and closing (see Figure 21-21).
		From such tracings, it is possible to determine the time that a channel is open (about 0.7 ms) and the ion flux through it (9900 Na ions/ms).
	www.ncbi.nlm.nih.gov /books/bv.fcgi?rid=mcb.section.6160 (2937 words)

	Understanding how voltage-gated ion channels operate
		Such channels can be extremely important; members of the voltage-gated ion channel family are crucial to generating electrical pulses in the brain and heart, carrying signals in nerves and muscles.
		According to Richard Horn, Ph.D., professor of physiology at Jefferson Medical College of Thomas Jefferson University in Philadelphia, voltage-gated ion channels are large proteins with a pore that pierces the cell membrane.
		They open and close in response to voltage changes across the cell membrane, and the channels determine when and which ions are permitted to cross a cell membrane.
	www.rxpgnews.com /research/biotechnology/article_2626.shtml (676 words)

	CNI Review Medical Journal - Online Library - Colorado Neurological Institute
		Voltage-gated ion channels are responsible for the generation and propagation of action potentials along electrically excitable membranes.
		Ion channels are fundamentally important for the conduction of impulses along the membranes of neurons, skeletal muscle, and cardiac muscle.
		These diseases are now called "channelopathies." Ion channels are normally responsible for the generation of electrical currents across excitable membranes, and the "channelopathies" are characterized by increased or decreased excitability of nerve or muscle.
	www.thecni.org /reviews/13-2-p02-england.htm (2520 words)

	Biophysical Journal: Electrostatic Model of S4 Motion in Voltage-Gated Ion Channels
		The S4 transmembrane domain of the family of voltage-gated ion channels is generally thought to be the voltage sensor, whose translocation by an applied electric field produces the gating current.
		Gating charge vs. voltage curves were generated from the model equations and compared to experimental data recorded from the wild-type channel and charge-neutralized mutants.
		Assuming that the energetics of gating is dominated by electrostatic forces between S4 charges and countercharges on neighboring transmembrane domains, we calculate the total energy as a function of transmembrane displacement and twist of the S4 domain.
	www.findarticles.com /p/articles/mi_qa3938/is_200311/ai_n9306208 (1122 words)

	Channelopathies: ion channel defects linked to heritable clinical disorders -- Felix 37 (10): 729 -- Journal of Medical Genetics
		from mutations in a gene encoding a voltage gated Na channel.
		A missense mutation in the sodium channel gene Scn8a is responsible for cerebellar ataxia in the mouse mutant jolting.
		Mutation of a new sodium channel gene, Scn8a, in the mouse mutant `motor endplate disease'.
	jmg.bmjjournals.com /cgi/content/full/37/10/729 (7432 words)

	Transport Across Cell Membranes
		The properties of ion channels can be studied by means of the patch clamp technique.
		Such measurements reveal that each channel is either fully open or fully closed; that is, facilitated diffusion through a single channel is "all-or-none".
		The accumulation of sodium ions outside of the cell draws water out of the cell and thus enables it to maintain osmotic balance (otherwise it would swell and burst from the inward diffusion of water).
	users.rcn.com /jkimball.ma.ultranet/BiologyPages/D/Diffusion.html (2786 words)

	Figure 9-9 The General Structure of Voltage-Gated Ion Channels
		For voltage-gated sodium channels and some types of potassium channels, a region near the N-terminus protrudes into the cytosol and forms an inactivating particle.
		The voltage-gated channels for sodium, potassium, and calcium ions all share the same basic structural themes.
		Figure 9-9 The General Structure of Voltage-Gated Ion Channels
	www.mun.ca /biology/desmid/brian/BIOL2060/CellBiol9/CB9_9.html (180 words)

	POSTSYNAPTIC POTENTIAL SUMMATION AND ACTION POTENTIAL INITIATION: FUNCTION FOLLOWING FORM -- Giuliodori and Zuccolilli 28 (2): 79 -- Advances in Physiology Education
		The uneven concentration of voltage-gated ion channels differentiates
		of voltage-gated ion channels, is adapted for action potential
		potentials depend on the activation of voltage-gated ion channels.
	advan.physiology.org /cgi/content/full/28/2/79 (483 words)

	Activation of NMDA receptors linked to modulation of voltage-gated ion channels and functional implications -- Davis and Linn 284 (3): C757 -- AJP - Cell Physiology
		voltage-gated ion channels (1, 2, 10, 40, 44).
		In the present study, we conducted experiments to explore the effect of NMDA receptor activation on voltage-gated ion channels
		When NMDA is applied to voltage-clamped cells, it opens nonselective cation channels that decrease the cell's input resistance.
	ajpcell.physiology.org /cgi/content/full/284/3/C757 (6870 words)

	APStracts 6:0266N, 1999.
		The role of dendritic voltage-gated ion channels in the generation of action potential bursting was investigated using whole-cell patch-clamp recordings from the soma and dendrites of CA1 pyramidal neurons located in hippocampal slices of adult rats.
		Dendritic voltage gated ion channels profoundly regulate the processing and storage of incoming information in CA1 pyramidal neurons by modulating the action potential firing mode from single spiking to burst firing.
		This suggest that the Ni-sensitive voltage-gated Ca2+ channels have the most important role in action potential burst generation.
	www.uth.tmc.edu /apstracts/1999/jn/June/266n.html (458 words)

	Immobilizing the Moving Parts of Voltage-gated Ion Channels -- Horn et al. 116 (3): 461 -- The Journal of General Physiology
		Keynes, R.D., and Elinder, F. The screw-helical voltage gating of ion channels.
		the inactivation gate of the sodium channel partly hinder its
		Armstrong, C.M., and Bezanilla, F. Inactivation of the sodium channel.
	www.jgp.org /cgi/content/full/116/3/461 (7970 words)

	Noise and stochastic resonance in voltage-gated ion channels -- Adair 100 (21): 12099 -- Proceedings of the National Academy of Sciences
		Noise and stochastic resonance in voltage-gated ion channels -- Adair 100 (21): 12099 -- Proceedings of the National Academy of Sciences
		the density of channels or by increasing the axon polarization.
		Membrane voltage variations, in the absence of noise, as a function of time after voltage pulses at a clock-time of 5 ms.
	www.pnas.org /cgi/content/full/100/21/12099 (3687 words)

	A Novel Extracellular Calcium Sensing Mechanism in Voltage-Gated Potassium Ion Channels -- Johnson et al. 21 (12): 4143 -- Journal of Neuroscience
		A Novel Extracellular Calcium Sensing Mechanism in Voltage-Gated Potassium Ion Channels -- Johnson et al.
		channels are unusually sensitive to external calcium concentration
		region during channel gating and defines a molecular mechanism
	www.jneurosci.org /cgi/content/abstract/21/12/4143 (622 words)

	Action potentials occur because of voltage gated ion channels
		This is due to the opening of voltage gated ion channels
		Action potentials occur because of voltage gated ion channels
		If the stimulating potential causes the membrane potential to rise about 15-20 mV an action potential results.
	www.wsu.edu /~rlee/biol103/lect16/tsld028.htm (46 words)

	IUPHAR ION CHANNEL COMPENDIUM - VOLTAGE-GATED ION CHANNELS
		IUPHAR ION CHANNEL COMPENDIUM - VOLTAGE-GATED ION CHANNELS
	www.iuphar-db.org /iuphar-ic/ionChannel.html (8 words)

	lec7.ppt
		You have to monitor a ligand-gated channel in voltage-clamp mode.
		Look up (web or book) some values for single-channel conductances and time-courses for the following channel types: AMPA-receptor NMDA-receptor GABA-A receptor Squid Na channel (voltage-gated) Squid K channel (voltage-gated) 3.
		Draw what would happen to the action potential if the squid sodium channel did not inactivate.
	www.ncbs.res.in /~events/neuro2003/lectures/lec7.ppt (837 words)

	73431.001207&ELEMENT_SET=DECL
		Ion channels which open in response to a change in the voltage across the membrane are referred to as voltage gated ion channels (or voltage-dependent ion channels).
		Ion channels which open in response to the binding of a ligand to the channel protein are referred to as ligand gated ion channels.
		Ligand gated ion channels may be described as ion channels which open in response to the binding of a ligand to the channel protein.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/73431.001207&ELEMENT_SET=DECL (8696 words)

	Second Messenger Cascades
		The second-messenger system can inherit its voltage-dependency from that of the ion channels in one of two ways: if the G-protein acts as a state sensor, the activation rate will be an S-shaped function of voltage; if instead it acts as a transition sensor, the rate will be a bell-shaped function of voltage.
		components to simultaneously dissociate from the channel protein, then the rate at which this occurs is proportional to the rate of ion channel state transitions.
		-subunit of an ion channel protein, at the center of which is the pore or P-region which allows selected species of ions to cross the membrane.
	www.klab.caltech.edu /~stemmler/s4node4.html (8696 words)

	Ion Channels for Beginners Page 4
		The three main groups of ion channels are 1) the voltage-gated channels such as the sodium and potassium channels of the nerve axons and nerve terminals, 2) the extracellular ligand-activated channels which includes channels such as GABA and glycine receptor channels, most of which are regulated by ligands that are "neurotransmitters".
		These neurotransmitter ligand-gated channels are not related to voltage-gated channels or to the glutamate ligand-gated ion channel.
		Murine myotonia and hyperekplexia are ion channel diseases caused by insertion of transposons.
	www2.montana.edu /cftr/IonChannelPrimers/beginners4.htm (9238 words)

	Ion Channels for Beginners Page 4
		The three main groups of ion channels are 1) the voltage-gated channels such as the sodium and potassium channels of the nerve axons and nerve terminals, 2) the extracellular ligand-activated channels which includes channels such as GABA and glycine receptor channels, most of which are regulated by ligands that are "neurotransmitters".
		These neurotransmitter ligand-gated channels are not related to voltage-gated channels or to the glutamate ligand-gated ion channel.
		Murine myotonia and hyperekplexia are ion channel diseases caused by insertion of transposons.
	opal.msu.montana.edu /cftr/IonChannelPrimers/beginners4.htm (9238 words)

	Outline for Jan
		Channels on the axon that let ions in are called- voltage-gated (as opposed to chemically gated) because they open and close depending on the electrical potential across the membrane.
		The cell body and dendrites don't have many of this kind (voltage-gated) of ion channel (so action potentials are restricted to axons, and graded potentials apply to dendrites and cell bodies).
		This causes (in 1 of 2 ways, stay tuned!) the chemically gated ion channels to open, causing depolarization (or hyperpol.
	www.arts.uwaterloo.ca /~bfleming/psych261/lec4se21.htm (9238 words)

	Ligand-gated ion channel - Wikipedia, the free encyclopedia
		The Ligand-gated ion channels, also referred to as LGICs, or ionotropic receptors, are a group of intrinsic transmembrane ion channels that are opened in response to binding of a chemical messenger, as opposed to voltage-gated ion channels or stretch-activated ion channels.
		The prototypic ligand-gated ion channel is the nicotinic acetylcholine receptor.
		The Ligand-gated ion channels are classified into four superfamilies: the Cys-loop receptors, the glutamate receptors, the TRP (transient receptor potential) channels and the ATP-gated channels.
	en.wikipedia.org /wiki/Ionotropic_receptor (383 words)

	Gating & Permeation
		Whereas the gating machinery resides in the pore region of the channel, the voltage sensor and ligand binding core are separate structural domains.
		Ion channels are unique among proteins because it is possible to experimentally study the behavior of individual channel molecules, using the patch clamp technique.
		Single channel analysis of drk1 pore mutants suggested that the selectivity filter is a dynamic structure, which controls permeation rate by switching between conformations that bind K ions with high and low affinity.
	www.duke.edu /~av8/vandongen_lab/project_1.htm (643 words)

	Ion Channel Links
		Voltage-sensitive and ligand-gated ion channels of the honeybee brain.
		Studies of biophysical and pharmacological properties of ligand gated ion channels, presynaptic mechanisms of transmitter release and properties of synaptically activated receptors.
		Database of nucleic and proteic sequences of various types of ligand-gated ion channel subunits by the Pasteur Institute.
	www.geocities.com /ionchannels (643 words)

	Ion Channel Links
		Voltage-sensitive and ligand-gated ion channels of the honeybee brain.
		Studies of biophysical and pharmacological properties of ligand gated ion channels, presynaptic mechanisms of transmitter release and properties of synaptically activated receptors.
		Main research areas: Characterization of ion channel populations, Intracellular Ca2+ sources, Effects of cyclic nucleotides and their stable analogues and Signal transduction pathways from hormone-receptor complex to contraction and relaxation.
	www.geocities.com /ionchannels (432 words)

	ionchann
		Research in Ion Channel Function: Sodium, calcium, and potassium ion channels are studied using single channel recording, whole-cell voltage clamp, video image analysis, and pharmacological manipulation.
		Lectures on ion channels, transporter and PCR by Tom Pressley as a Wellcome Visiting Professor in the Basic Medical Sciences at the University of Northern Iowa, October 19-23, 1998.
		This is an ambitious attempt to create a resource page for the ion channel community and serves as a gateway to all the resources containing relevant information on ion channels.
	www.ttuhsc.edu /SOM/physiology/Neely/ionchann.htm (1340 words)

	Structure of the Pore-forming Transmembrane Domain of a Ligand-gated Ion Channel -- Méthot et al. 276 (26): 23726 -- Journal of Biological Chemistry
		Torpedo analog of the voltage-dependent transmembrane anion channel
		Structure of the Pore-forming Transmembrane Domain of a Ligand-gated Ion Channel -- Méthot et al.
		of the ligand-gated ion channel superfamily is formed from five
	www.jbc.org /cgi/content/full/276/26/23726 (3798 words)

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