Ligand-gated ion channel
Encyclopedia
Ligand-gated ion channels (LGICs) are one type of ionotropic receptor or channel-linked receptor
. They are a group of transmembrane ion channel
s that are opened or closed in response to the binding of a chemical messenger (i.e., a ligand
), such as a neurotransmitter
.
The binding site of endogenous ligands on LGICs protein complexes are normally located on a different portion of the protein (an allosteric
binding site) compared to where the ion conduction pore is located. The direct link between ligand binding and opening or closing of the ion channel, which is characteristic of ligand-gated ion channels, is contrasted with the indirect function of metabotropic receptor
s, which use second messenger
s. LGICs are also different from voltage-gated ion channel
s (which open and close depending on membrane potential
), and stretch-activated ion channel
s (which open and close depending on mechanical deformation of the cell membrane
).
is regulated by a ligand
and is usually very selective to one or more ions like Na+
, K+
, Ca2+
, or Cl-
. Such receptors located at synapse
s convert the chemical signal of presynaptically released neurotransmitter directly and very quickly into a postsynaptic electrical signal.
Many LGICs are additionally modulated by allosteric ligands
, by channel blockers, ion
s, or the membrane potential
.
ic channels consist of the extracellular ligand-binding domain and a transmembrane domain. Each transmembrane domain in the pentamer includes four transmembrane helix
es.
. It consists of a pentamer of protein subunits, with two binding sites for acetylcholine
, which, when bound, alter the receptor's configuration and cause an internal pore to open. This pore allowed Na+ ions to flow down their electrochemical gradient
into the cell. With a sufficient number of channels opening at once, the intracellular Na+ concentration rises to the point at which the positive charge within the cell
is enough to depolarize the membrane
, and an action potential
is initiated.
at the genetic level. LGICs are classified into three superfamilies:
contain a characteristic loop formed by a disulfide bond between two cysteine
residues and are subdivided into the type of ion that the corresponding channel conducts (anionic or cationic) and further into families defined by the endogenous ligand. They are usually pentameric.
Vertebrate Anionic Cys-loop Receptors
Vertebrate Cationic Cys-loop Receptors
s bind the neurotransmitter
glutamate
. They form tetramers.
ATP
. They form trimers.
have their effects, although unequivocal evidence of this is yet to be established. In particular, the GABA
and NMDA
receptors are affected by anaesthetic agents at concentrations similar to those used in clinical anaesthesia.
Ion channel linked receptors
Ion channel linked receptors are cell membrane bound receptors. They act through synaptic signaling on electrically excitable cells. The ion channels opening and closing is controlled by neurotransmitters....
. They are a group of transmembrane ion channel
Ion channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...
s that are opened or closed in response to the binding of a chemical messenger (i.e., a ligand
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...
), such as a neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
.
The binding site of endogenous ligands on LGICs protein complexes are normally located on a different portion of the protein (an allosteric
Allosteric regulation
In biochemistry, allosteric regulation is the regulation of an enzyme or other protein by binding an effector molecule at the protein's allosteric site . Effectors that enhance the protein's activity are referred to as allosteric activators, whereas those that decrease the protein's activity are...
binding site) compared to where the ion conduction pore is located. The direct link between ligand binding and opening or closing of the ion channel, which is characteristic of ligand-gated ion channels, is contrasted with the indirect function of metabotropic receptor
Metabotropic receptor
Metabotropic receptor is a subtype of membrane receptors at the surface or in vesicles of eukaryotic cells.In the nervous system, based on their structural and functional characteristics, neurotransmitter receptors can be classified into two broad categories: metabotropic and ionotropic receptors...
s, which use second messenger
Second messenger system
Second messengers are molecules that relay signals from receptors on the cell surface to target molecules inside the cell, in the cytoplasm or nucleus. They relay the signals of hormones like epinephrine , growth factors, and others, and cause some kind of change in the activity of the cell...
s. LGICs are also different from voltage-gated ion channel
Voltage-gated ion channel
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....
s (which open and close depending on membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
), and stretch-activated ion channel
Stretch-activated ion channel
Stretch-activated or stretch-gated ion channels are ion channels which open their pores in response to mechanical deformation of a neuron's plasma membrane. Stretch-activated channels were first observed in chick skeletal muscles by Falguni Guharay and Frederick Sachs in 1983 and the results were...
s (which open and close depending on mechanical deformation of the cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
).
Regulation
The ion channelIon channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...
is regulated by a ligand
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...
and is usually very selective to one or more ions like Na+
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
, K+
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, Ca2+
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
, or Cl-
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
. Such receptors located at synapse
Synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
s convert the chemical signal of presynaptically released neurotransmitter directly and very quickly into a postsynaptic electrical signal.
Many LGICs are additionally modulated by allosteric ligands
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...
, by channel blockers, ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s, or the membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...
.
Structure
Each subunit of the pentamerPentamer
A pentamer is a thing composed out of five sub-units.In chemistry, it applies to molecules made of five monomers.In biochemistry, it applies to macromolecules, in particular to pentameric proteins, made of five proteic sub-units....
ic channels consist of the extracellular ligand-binding domain and a transmembrane domain. Each transmembrane domain in the pentamer includes four transmembrane helix
Transmembrane helix
Transmembrane domain usually denotes a single transmembrane alpha helix of a transmembrane protein. It is called a "domain" because an alpha-helix in a membrane can fold independently from the rest of the protein, similar to domains of water-soluble proteins...
es.
Example: nicotinic acetylcholine receptor
The prototypic ligand-gated ion channel is the nicotinic acetylcholine receptorNicotinic acetylcholine receptor
Nicotinic acetylcholine receptors, or nAChRs, are cholinergic receptors that form ligand-gated ion channels in the plasma membranes of certain neurons and on the postsynaptic side of the neuromuscular junction...
. It consists of a pentamer of protein subunits, with two binding sites for acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
, which, when bound, alter the receptor's configuration and cause an internal pore to open. This pore allowed Na+ ions to flow down their electrochemical gradient
Electrochemical gradient
An electrochemical gradient is a spatial variation of both electrical potential and chemical concentration across a membrane; that is, a combination of the membrane potential and the pH gradient...
into the cell. With a sufficient number of channels opening at once, the intracellular Na+ concentration rises to the point at which the positive charge within the cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
is enough to depolarize the membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
, and an action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
is initiated.
Classification
Many important ion channels are ligand-gated, and they show a significant degree of homologyHomology (biology)
Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
at the genetic level. LGICs are classified into three superfamilies:
Cys-loop receptors
The cys-loop receptorsCys-loop receptors
The Cys-loop ligand-gated ion channel superfamily is composed of nicotinic acetylcholine, GABAA, GABAA-ρ, glycine and 5-HT3 receptors that are composed of five protein subunits that form a pentameric arrangement around a central pore. There are usually 2 alpha subunits and 3 other beta, gamma, or...
contain a characteristic loop formed by a disulfide bond between two cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
residues and are subdivided into the type of ion that the corresponding channel conducts (anionic or cationic) and further into families defined by the endogenous ligand. They are usually pentameric.
Vertebrate Anionic Cys-loop Receptors
| Type | Class | IUPHAR-recommended protein name |
Gene | Previous names |
|---|---|---|---|---|
| GABAA | alpha | α1 GABRA1 Gamma-aminobutyric acid receptor subunit alpha-1 is a protein that in humans is encoded by the GABRA1 gene.-Further reading:... α2 GABRA2 Gamma-aminobutyric acid receptor subunit alpha-2 is a protein that in humans is encoded by the GABRA2 gene.... α3 GABRA3 Gamma-aminobutyric acid receptor subunit alpha-3 is a protein that in humans is encoded by the GABRA3 gene.- Function :GABA is the major inhibitory neurotransmitter in the mammalian brain where it acts at GABAA receptors, which are ligand-gated chloride channels... α4 GABRA4 Gamma-aminobutyric acid receptor subunit alpha-4 is a protein that in humans is encoded by the GABRA4 gene.... α5 GABRA5 Gamma-aminobutyric acid A receptor, alpha 5, also known as GABRA5, is a protein which in humans is encoded by the GABRA5 gene.-Function:... α6 GABRA6 Gamma-aminobutyric acid receptor subunit alpha-6 is a protein that in humans is encoded by the GABRA6 gene.One study has found a genetic variant in the gene to be associated with the personality trait neuroticism.... |
|
EJM, ECA4 |
| beta | β1 GABRB1 Gamma-aminobutyric acid receptor subunit beta-1 is a protein that in humans is encoded by the GABRB1 gene.... β2 GABRB2 Gamma-aminobutyric acid receptor subunit beta-2 is a protein that in humans is encoded by the GABRB2 gene.... β3 GABRB3 Gamma-aminobutyric acid receptor subunit beta-3 is a protein that in humans is encoded by the GABRB3 gene.... |
|
ECA5 |
|
| gamma | γ1 GABRG1 Gamma-aminobutyric acid receptor subunit gamma-1 is a protein that in humans is encoded by the GABRG1 gene. The protein encoded by this gene is a subunit of the GABAA receptor.Variants of this gene may be associated with alcohol dependence.... γ2 GABRG2 Gamma-aminobutyric acid receptor subunit gamma-2 is a protein that in humans is encoded by the GABRG2 gene.-Interactions:GABRG2 has been shown to interact with GABARAP and Dopamine receptor D5.-Further reading:... γ3 GABRG3 GABAA receptor-γ3, also known as GABRG3, is a protein which in humans is encoded by the GABRG3 gene.- Function :GABRG3 is a subunit of the GABAA receptor for the neurotransmitter gamma-Aminobutyric acid .- Association with alcoholism :... |
|
CAE2, ECA2, GEFSP3 | |
| delta | δ GABRD Gamma-aminobutyric acid receptor subunit delta is a protein that in humans is encoded by the GABRD gene.... |
|||
| epsilon | ε GABRE Gamma-aminobutyric acid receptor subunit epsilon is a protein that in humans is encoded by the GABRE gene.... |
|||
| pi | π GABRP Gamma-aminobutyric acid receptor subunit pi is a protein that in humans is encoded by the GABRP gene.... |
|||
| theta | θ GABRQ Gamma-aminobutyric acid receptor subunit theta is a protein that in humans is encoded by theGABRQ gene. The protein encoded by this gene is a subunit of the GABAA receptor.... |
|||
| rho | ρ1 GABRR1 Gamma-aminobutyric acid receptor subunit rho-1 is a protein that in humans is encoded by the GABRR1 gene.- External links :... ρ2 GABRR2 Gamma-aminobutyric acid receptor subunit rho-2 is a protein that in humans is encoded by the GABRR2 gene.- External links :... ρ3 GABRR3 Gamma-aminobutyric acid receptor subunit rho-3 is a protein that in humans is encoded by the GABRR3 gene. The protein encoded by this gene is a subunit of the GABAA-ρ receptor.... |
|
GABAC | |
| Glycine Glycine receptor The glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current... (GlyR) |
alpha | α1 GLRA1 Glycine receptor subunit alpha-1 is a protein that in humans is encoded by the GLRA1 gene.-Further reading:... α2 GLRA2 Glycine receptor subunit alpha-2 is a protein that in humans is encoded by the GLRA2 gene.... α3 GLRA3 The Glycine receptor subunit alpha-3 is a protein that in humans is encoded by the GLRA3 gene. The protein encoded by this gene is a subunit of the glycine receptor.Variants of this receptor subunit is associated with susceptibility to epilepsy.... α4 GLRA4 The glycine receptor, alpha 4, also known as GLRA4, is a human pseudogene. The protein encoded by this gene is a subunit of the glycine receptor.... |
|
STHE |
| beta | β GLRB Glycine receptor subunit beta is a protein that in humans is encoded by the GLRB gene.-Further reading:... |
Vertebrate Cationic Cys-loop Receptors
| Type | Class | IUPHAR-recommended protein name |
Gene | Previous names |
|---|---|---|---|---|
| Serotonin (5-HT) |
5-HT3 5-HT3 receptor The 5-HT3 receptor is a member of the superfamily of ligand-gated ion channels, a superfamily that also includes the neuronal nicotinic acetylcholine receptors , and the inhibitory neurotransmitter receptors for GABA and glycine... |
5-HT3A HTR3A 5-hydroxytryptamine receptor 3A is a protein that in humans is encoded by the HTR3A gene.... 5-HT3B HTR3B 5-hydroxytryptamine receptor 3B, also known as HTR3B, is a human gene. The protein encoded by this gene is a subunit of the 5-HT3 receptor.... 5-HT3C HTR3C 5-hydroxytryptamine receptor 3C is a protein that in humans is encoded by the HTR3C gene. The protein encoded by this gene is a subunit of the 5-HT3 receptor.... 5-HT3D HTR3D 5-hydroxytryptamine receptor 3D is a protein that in humans is encoded by the HTR3D gene. The protein encoded by this gene is a subunit of the 5-HT3 receptor.-External links:... 5-HT3E HTR3E 5-hydroxytryptamine receptor 3E is a protein that in humans is encoded by the HTR3E gene. The protein encoded by this gene is a subunit of the 5-HT3 receptor.... |
|
5-HT3A 5-HT3B 5-HT3C 5-HT3D 5-HT3E |
| Nicotinic acetylcholine Nicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are cholinergic receptors that form ligand-gated ion channels in the plasma membranes of certain neurons and on the postsynaptic side of the neuromuscular junction... (nAChR) |
alpha | α1 CHRNA1 Acetylcholine receptor subunit alpha is a protein that in humans is encoded by the CHRNA1 gene.-Interactions:Cholinergic receptor, nicotinic, alpha 1 has been shown to interact with CHRND.... α2 CHRNA2 Neuronal acetylcholine receptor subunit alpha-2 is a protein that in humans is encoded by the CHRNA2 gene.... α3 CHRNA3 Neuronal acetylcholine receptor subunit alpha-3 is a protein that in humans is encoded by the CHRNA3 gene.- Interactive pathway map :... α4 CHRNA4 Neuronal acetylcholine receptor subunit alpha-4 is a protein that in humans is encoded by the CHRNA4 gene.... α5 CHRNA5 Neuronal acetylcholine receptor subunit alpha-5 is a protein that in humans is encoded by the CHRNA5 gene.- Function :Nicotinic acetylcholine receptors , such as CHRNA5, are members of a superfamily of ligand-gated ion channels that mediate fast signal transmission at synapses. The nAChRs are... α6 CHRNA6 Cholinergic receptor, nicotinic, alpha 6, also known as CHRNA6, is a human gene, which codes for the α6 subunit found in certain types of nicotinic acetylcholine receptors found primarily in the brain... α7 CHRNA7 Neuronal acetylcholine receptor subunit alpha-7 is a protein that in humans is encoded by the CHRNA7 gene.-See also:* Alpha-7 nicotinic receptor* Nicotinic acetylcholine receptor* Acetylcholine receptor... α9 CHRNA9 Neuronal acetylcholine receptor subunit alpha-9 is a protein that in humans is encoded by the CHRNA9 gene.Selective block of α9α10 nicotinic acetylcholine receptors by the conotoxin RgIA has been shown to be analgesic in an animal model of nerve injury pain.... α10 CHRNA10 Neuronal acetylcholine receptor subunit alpha-10 also known as cholinergic receptor nicotinic alpha 10 is a protein that in humans is encoded by the CHRNA10 gene... |
|
ACHRA, ACHRD, CHRNA, CMS2A, FCCMS, SCCMS |
| beta | β1 CHRNB1 Acetylcholine receptor subunit beta is a protein that in humans is encoded by the CHRNB1 gene.... β2 CHRNB2 Neuronal acetylcholine receptor subunit beta-2 is a protein that in humans is encoded by the CHRNB2 gene.... β3 CHRNB3 Neuronal acetylcholine receptor subunit beta-3 is a protein that in humans is encoded by the CHRNB3 gene.... β4 CHRNB4 Neuronal acetylcholine receptor subunit beta-4 is a protein that in humans is encoded by the CHRNB4 gene.... |
|
CMS2A, SCCMS, ACHRB, CHRNB, CMS1D EFNL3, nAChRB2 |
|
| gamma | γ CHRNG Acetylcholine receptor subunit gamma is a protein that in humans is encoded by the CHRNG gene.-Further reading:... |
ACHRG | ||
| delta | δ CHRND Acetylcholine receptor subunit delta is a protein that in humans is encoded by the CHRND gene.-Interactions:CHRND has been shown to interact with Cholinergic receptor, nicotinic, alpha 1.... |
ACHRD, CMS2A, FCCMS, SCCMS | ||
| epsilon | ε CHRNE Acetylcholine receptor subunit epsilon is a protein that in humans is encoded by the CHRNE gene.... |
ACHRE, CMS1D, CMS1E, CMS2A, FCCMS, SCCMS | ||
| Zinc-activated ion channel Zinc-activated ion channel Zinc-activated ion channel , is a human protein encoded by the gene. ZAC forms a cation-permeable ligand-gated ion channel of the "Cys-loop" superfamily... (ZAC) |
ZAC | ZAC1, L2m LGICZ, LGICZ1 |
Ionotropic glutamate receptors
The ionotropic glutamate receptorIonotropic glutamate receptor
The ability of synapses to modify their synaptic strength in response to activity is a fundamental property of the nervous system and may be an essential component of learning and memory. There are three classes of ionotropic glutamate receptor, namely NMDA , AMPA and kainate receptors...
s bind the neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
glutamate
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
. They form tetramers.
| Type | Class | IUPHAR-recommended protein name |
Gene | Previous names |
|---|---|---|---|---|
| AMPA AMPA receptor The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor is a non-NMDA-type ionotropic transmembrane receptor for glutamate that mediates fast synaptic transmission in the central nervous system . Its name is derived from its ability to be activated by the artificial glutamate analog AMPA... |
GluA | GluA1 GRIA1 Glutamate receptor 1 is a protein that in humans is encoded by the GRIA1 gene.Glutamate receptors are the predominant excitatory neurotransmitter receptors in the mammalian brain and are activated in a variety of normal neurophysiologic processes... GluA2 GRIA2 Glutamate receptor 2 is a protein that in humans is encoded by the GRIA2 gene.- Function :Glutamate receptors are the predominant excitatory neurotransmitter receptors in the mammalian brain and are activated in a variety of normal neurophysiologic processes... GluA3 GRIA3 Glutamate receptor 3 is a protein that in humans is encoded by the GRIA3 gene.- Function :Glutamate receptors are the predominant excitatory neurotransmitter receptors in the mammalian brain and are activated in a variety of normal neurophysiologic processes... GluA4 GRIA4 Glutamate receptor 4 is a protein that in humans is encoded by the GRIA4 gene.-Interactions:GRIA4 has been shown to interact with CACNG2, GRIP1, PICK1 and PRKCG.-RNA editing:... |
|
GLUA1, GluR1, GluRA, GluR-A, GluR-K1, HBGR1 GLUA2, GluR2, GluRB, GluR-B, GluR-K2, HBGR2 GLUA3, GluR3, GluRC, GluR-C, GluR-K3 GLUA4, GluR4, GluRD, GluR-D |
| Kainate Kainate receptor Kainate receptors, or KARs, are non-NMDA ionotropic receptors which respond to the neurotransmitter glutamate. They were first identified as a distinct receptor type through their selective activation by the agonist kainate, a drug first isolated from red algae Digenea simplex. KARs are less well... |
GluK | GluK1 GRIK1 Glutamate receptor, ionotropic, kainate 1, also known as GRIK1, is a protein that in humans is encoded by the GRIK1 gene.- Function :... GluK2 GRIK2 Glutamate receptor, ionotropic kainate 2 is a protein that in humans is encoded by the GRIK2 gene.- Clinical significance :Homozygosity for a GRIK2 deletion-inversion mutation is associated with nonsyndromic autosomal recessive mental retardation.... GluK3 GRIK3 Glutamate receptor, ionotropic kainate 3 is a protein that in humans is encoded by the GRIK3 gene.... GluK4 GRIK4 GRIK4 is a kainate receptor subtype belonging to the family of ligand-gated ion channels which is encoded by the gene.-Function:... GluK5 GRIK5 Glutamate receptor, ionotropic kainate 5 is a protein that in humans is encoded by the GRIK5 gene.-Interactions:GRIK5 has been shown to interact with DLG4 and GRIK2.... |
|
GLUK5, GluR5, GluR-5, EAA3 GLUK6, GluR6, GluR-6, EAA4 GLUK7, GluR7, GluR-7, EAA5 GLUK1, KA1, KA-1, EAA1 GLUK2, KA2, KA-2, EAA2 |
| NMDA NMDA receptor The NMDA receptor , a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function.... |
GluN | GluN1 GRIN1 Glutamate [NMDA] receptor subunit zeta-1 is a protein that in humans is encoded by the GRIN1 gene.-Further reading:... NRL1A GRINL1A GRINL1A complex locus protein 1 is a protein that in humans is encoded by the GRINL1A gene.... NRL1B GRINL1B Glutamate receptor, ionotropic, N-methyl D-aspartate-like 1B, also known as GRINL1B, is a human gene. The protein encoded by this gene is a subunit of the NMDA receptor.... |
|
GLUN1, NMDA-R1, NR1, GluRξ1 |
| GluN2A GRIN2A Glutamate [NMDA] receptor subunit epsilon-1 is a protein that in humans is encoded by the GRIN2A gene.-Interactions:GRIN2A has been shown to interact with FYN, DLG4, DLG3, DLG1, Src, PTK2B and Interleukin 16.-Further reading:... GluN2B GRIN2B Glutamate [NMDA] receptor subunit epsilon-2 also known as N-methyl D-aspartate receptor subtype 2B is a protein that in humans is encoded by the GRIN2B gene.- Function :... GluN2C GRIN2C Glutamate [NMDA] receptor subunit epsilon-3 is a protein that in humans is encoded by the GRIN2C gene.-Interactions:GRIN2C has been shown to interact with DLG4 and DLG3.... GluN2D GRIN2D Glutamate [NMDA] receptor subunit epsilon-4 is a protein that in humans is encoded by the GRIN2D gene.-Interactions:GRIN2D has been shown to interact with Interleukin 16.... |
|
GLUN2A, NMDA-R2A, NR2A, GluRε1 GLUN2B, NMDA-R2B, NR2B, hNR3, GluRε2 GLUN2C, NMDA-R2C, NR2C, GluRε3 GLUN2D, NMDA-R2D, NR2D, GluRε4 |
||
| GluN3A GRIN2A Glutamate [NMDA] receptor subunit epsilon-1 is a protein that in humans is encoded by the GRIN2A gene.-Interactions:GRIN2A has been shown to interact with FYN, DLG4, DLG3, DLG1, Src, PTK2B and Interleukin 16.-Further reading:... GluN3B GRIN3B Glutamate [NMDA] receptor subunit 3B is a protein that in humans is encoded by the GRIN3B gene.... |
|
GLUN3A, NMDA-R3A, NMDAR-L, chi-1 GLU3B, NMDA-R3B |
||
| ‘Orphan’ | (GluD) | GluD1 GRID1 Glutamate receptor delta-1 subunit also known as GluD1 or GluRδ1 is a protein that in humans is encoded by the GRID1 gene.- Function :This gene encodes a subunit of glutamate receptor ligand-gated ion channel... GluD2 GRID2 Glutamate receptor, ionotropic, delta 2, also known as GluD2, GluRδ2, or δ2, is a protein that in humans is encoded by the GRID2 gene.... |
|
GluRδ1 GluRδ2 |
ATP-gated channels
ATP-gated channels open in response to binding the nucleotideNucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
. They form trimers.
| Type | Class | IUPHAR-recommended protein name |
Gene | Previous names |
|---|---|---|---|---|
| P2X P2X Receptor P2X receptors are a family of cation-permeable ligand gated ion channels that open in response to the binding of extracellular adenosine 5'-triphosphate . They belong to a larger family of receptors known as the purinergic receptors... |
N/A | P2X1 P2RX1 P2X purinoceptor 1 is a protein that in humans is encoded by the P2RX1 gene.... P2X2 P2RX2 P2X purinoceptor 2 is a protein that in humans is encoded by the P2RX2 gene.... P2X3 P2RX3 P2X purinoceptor 3 is a protein that in humans is encoded by the P2RX3 gene.... P2X4 P2RX4 P2X purinoceptor 4 is a protein that in humans is encoded by the P2RX4 gene.... P2X5 P2RX5 P2X purinoceptor 5 is a protein that in humans is encoded by the P2RX5 gene.... P2X6 P2RX6 P2X purinoceptor 6 is a protein that in humans is encoded by the P2RX6 gene.... P2X7 P2RX7 P2X purinoceptor 7 is a protein that in humans is encoded by the P2RX7 gene.-Recruitment of pannexin:Activation of the P2RX7 receptor by ATP leads to recruitment of pannexin pores which allow small molecules such as ATP to leak out of cells. This allows further activation of purinergic receptors... |
|
P2X1 P2X2 P2X3 P2X4 P2X5 P2X6 P2X7 |
Clinical relevance
Ligand-gated ion channels are likely to be the major site at which anaesthetic agents and ethanolEthanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
have their effects, although unequivocal evidence of this is yet to be established. In particular, the GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
and NMDA
NMDA
N-Methyl-D-aspartic acid or N-Methyl-D-aspartate is an amino acid derivative which acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor...
receptors are affected by anaesthetic agents at concentrations similar to those used in clinical anaesthesia.
See also
- ChronotropicChronotropicChronotropic effects are those that change the heart rate.Chronotropic drugs may change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node...
- Receptor (biochemistry)Receptor (biochemistry)In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
- Glycine receptorGlycine receptorThe glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current...
- P2X ReceptorP2X ReceptorP2X receptors are a family of cation-permeable ligand gated ion channels that open in response to the binding of extracellular adenosine 5'-triphosphate . They belong to a larger family of receptors known as the purinergic receptors...
- Sodium ion channelSodium ion channelSodium channels are integral membrane proteins that form ion channels, conducting sodium ions through a cell's plasma membrane. They are classified according to the trigger that opens the channel for such ions, i.e...
External links
- Ligand-Gated Ion Channel database at European Bioinformatics InstituteEuropean Bioinformatics InstituteThe European Bioinformatics Institute is a centre for research and services in bioinformatics, and is part of European Molecular Biology Laboratory...
. Verified availability April 11, 2007.