Information about Cyclic Nucleotide Gated Ion Channel
A cyclic nucleotide-gated ion channel is any ion channel that opens in the presence of cyclic nucleotides.
Other examples include the following "hyperpolarization activated cyclic nucleotide-gated potassium channels" (HCN): HCN1, HCN2, HCN3, HCN4
The retina is a thin layer of neural cells that lines the back of the eyeball of vertebrates and some cephalopods. It is comparable to the film in a camera.
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Mechanism
The channels are gated by a chemical ligand (the cyclic nucleotide) but they are more similar in structure to the family of voltage-gated ion channels than to the ligand gated ones. In fact, the cyclic nucleotide-gated channels often have positively or negatively charged areas that may respond to changes in membrane potential. The purpose and function of these charged areas are not yet fully understood.Functions
Cyclic nucleotide-gated channels are particularly important in several systems:- The mammalian olfactory system.[1]
- In the visual system, a cGMP (cyclic guanosine monophosphate) gated channel is found in the outer membrane of retinal photoreceptor cells. In response to high levels of cGMP, the channels are open and allow positively charged ions to flow into the cell, causing depolarization. This is the state of the cell in the dark (called the dark current), but a photon striking a photoreceptor in the cell causes a chain reaction that results in lower levels of cGMP and therefore hyperpolarization. Thus, these cells are actually more active in dark than in light.
- Funny currents have been associated with the HCN channels.[2]
Examples
"Cyclic nucleotide gated channel alpha" subunits include CNGA1, CNGA2, CNGA3, and CNGA4. "Beta" subunits include CNGB1 and CNGB3.Other examples include the following "hyperpolarization activated cyclic nucleotide-gated potassium channels" (HCN): HCN1, HCN2, HCN3, HCN4
References
1. ^ Jenkins PM, Hurd TW, Zhang L, et al (2006). "Ciliary targeting of olfactory CNG channels requires the CNGB1b subunit and the kinesin-2 motor protein, KIF17". Curr. Biol. 16 (12): 1211-6. DOI:10.1016/j.cub.2006.04.034. PMID 16782012.
2. ^ DiFrancesco D (2006). "Serious workings of the funny current". Prog. Biophys. Mol. Biol. 90 (1-3): 13-25. DOI:10.1016/j.pbiomolbio.2005.05.001. PMID 15975637.
2. ^ DiFrancesco D (2006). "Serious workings of the funny current". Prog. Biophys. Mol. Biol. 90 (1-3): 13-25. DOI:10.1016/j.pbiomolbio.2005.05.001. PMID 15975637.
External links
- MeSH cyclic-nucleotide+gated+ion+channels
- Overview at wustl.edu
Membrane transport protein: ion channels | |
|---|---|
| Ca2+: Calcium channel | Voltage-dependent calcium channel (L-type/CACNA1C, N-type, P-type, Q-type, R-type, T-type) - Inositol triphosphate receptor - Ryanodine receptor - Cation channels of sperm |
| Na+: Sodium channel | Nav1.4 - Nav1.5 - Nav1.7 - Epithelial sodium channel |
| K+: Potassium channel | Voltage-gated (KvLQT1, KvLQT2, KvLQT3, HERG, Shaker gene, KCNE1) - Calcium-activated (BK channel, SK channel, SK3) - Inward-rectifier (ROMK, KCNJ2, KCNJ11) - Tandem pore domain |
| Cl-: Chloride channel | Cystic fibrosis transmembrane conductance regulator |
| Porin | Aquaporin (1, 2, 3, 4) - Voltage-dependent anion channel |
| Cations: TRP | TRPA - TRPC (TRPC6) - TRPM (TRPM6) - TRPML (Mucolipin-1) - TRPP - TRPV (TRPV1, TRPV6) |
| Other/general | Gap junction - Stretch-activated ion channel - Ligand-gated ion channel - Voltage-gated ion channel - Cyclic nucleotide-gated ion channel - Two-pore channel |
Ion channels are pore-forming proteins that help to establish and control the small voltage gradient across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient.
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cyclic nucleotide is any nucleotide in which the phosphate group is bonded to two of the sugar's hydroxyl groups, forming a cyclical or ring structure.
These include:
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These include:
- cyclic AMP
- cyclic GMP
- cyclic ADP-ribose
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Voltage-gated ion channels are a class of transmembrane ion channels that are activated by changes in electrical potential difference near the channel; these types of ion channels are especially critical in neurons, but are common in many types of cells.
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The Ligand-gated ion channels, also referred to as LGICs, or ionotropic receptors, are a group of intrinsic transmembrane ion channels that are opened or closed in response to binding of a chemical messenger, as opposed to voltage-gated ion channels or
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Membrane potential (or transmembrane potential or transmembrane potential difference or transmembrane potential gradient), is the electrical potential difference (voltage) across a cell's plasma membrane.
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The olfactory system is the sensory system used for olfaction. Most mammals and reptiles have two distinct parts to their olfactory system: a main olfactory system and an accessory olfactory system.
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The visual system is the part of the nervous system which allows organisms to see. It interprets the information from visible light to build a representation of the world surrounding the body.
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Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP, most notably by activating intracellular protein kinases in response to the binding of membrane-impermeable peptide
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- For the moth genus, see Retina (moth).
The retina is a thin layer of neural cells that lines the back of the eyeball of vertebrates and some cephalopods. It is comparable to the film in a camera.
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photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eye's retina that is capable of phototransduction. More specifically, the photoreceptor absorbs photons from the visual field and signals this information to other neurons through a change in
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In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations.
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Photoreceptor can refer to:
In anatomy/cell biology:
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In anatomy/cell biology:
- Photoreceptor cell: a photosensitive cell, most commonly referring to a specialized type of neuron found in the retina of vertebrate eyes that is capable of phototransduction;
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Hyperpolarization is any change in a cell's membrane potential that makes it more polarized. That is, hyperpolarization is an increase in the absolute value of a cell's membrane potential.
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Funny current (or funny channel, or If) refers to a specific current in the heart. It is called "funny" because it has effects opposite to those of most other heart currents.
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Hyperpolarization has several meanings:
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- In biology, hyperpolarization (biology) occurs when the strength of the electric field across the width of a cell membrane increases.
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potassium channels are the most common type of ion channel. They form potassium-selective pores that span cell membranes. Potassium channels are found in most cells and control cell function.
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digital object identifier (or DOI) is a permanent identifier given to a document, which is not related to its current location. A typical use of a DOI is to give a scientific paper or article a unique identifying number that can be used by anyone to locate details of the paper, and
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digital object identifier (or DOI) is a permanent identifier given to a document, which is not related to its current location. A typical use of a DOI is to give a scientific paper or article a unique identifying number that can be used by anyone to locate details of the paper, and
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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A membrane transport protein (or simply transporter) is a protein involved in the movement of ions, small molecules, or macromolecules, such as another protein across a biological membrane.
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Ion channels are pore-forming proteins that help to establish and control the small voltage gradient across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient.
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A Calcium channel is an ion channel which displays selective permeabiltiy to calcium ions.
Examples include the voltage-dependent calcium channels and the inositol triphosphate receptor.
Calcium channel blockers are used to treat hypertension.
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Examples include the voltage-dependent calcium channels and the inositol triphosphate receptor.
Calcium channel blockers are used to treat hypertension.
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This article or section may be confusing or unclear for some readers.
Please [improve the article] or discuss this issue on the talk page. This article has been tagged since December 2006.
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Please [improve the article] or discuss this issue on the talk page. This article has been tagged since December 2006.
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The L-type calcium channel is a type of voltage-dependent calcium channel. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
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CACNA1C is a gene which codes a L-type voltage-dependent calcium channel associated with a variant of Long QT syndrome called Timothy's syndrome and also with brugada syndrome.
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N-type calcium channel is a type of voltage-dependent calcium channel. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
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The p-type calcium channel is a type of voltage-dependent calcium channel. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
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The Q-type calcium channel is a type of voltage-dependent calcium channel. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
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The R-type calcium channel is a type of voltage-dependent calcium channel. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties.
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Identifiers
Symbol CACNA1H
Entrez 8912
HUGO 1395
OMIM 607904
RefSeq NM_001005407
UniProt O95180
Other data
Locus Chr. 16 p13.3 The T-type calcium channel is a type of voltage-dependent calcium channel.
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Symbol CACNA1H
Entrez 8912
HUGO 1395
OMIM 607904
RefSeq NM_001005407
UniProt O95180
Other data
Locus Chr. 16 p13.3 The T-type calcium channel is a type of voltage-dependent calcium channel.
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