Ion channel: Difference between revisions

Latest revision as of 14:22, 21 February 2025

Protein that allows ions to pass through it

Ion channels are proteins found in the cell membrane that allow ions to pass into and out of the cell. These channels are crucial for a variety of physiological processes, including the generation of action potentials in neurons, the regulation of heart rate, and the release of hormones.

Structure[edit]

Ion channels are typically composed of multiple subunits that form a pore through which ions can pass. The structure of these channels can vary significantly, but they generally have a selectivity filter that determines which ions can pass through. The channels can be classified based on the type of ions they conduct, such as sodium channels, potassium channels, calcium channels, and chloride channels.

Function[edit]

Ion channels play a critical role in maintaining the resting membrane potential of cells and in the propagation of action potentials. They are involved in signal transduction and are essential for the function of muscles and nerves. Ion channels can be gated by various stimuli, including changes in voltage, binding of ligands, or mechanical forces.

Voltage-gated ion channels[edit]

Animation of a voltage-gated ion channel opening and closing

Voltage-gated ion channels open or close in response to changes in the membrane potential. These channels are crucial for the initiation and propagation of action potentials in neurons and muscle cells.

Ligand-gated ion channels[edit]

Ligand-gated ion channels open in response to the binding of a specific neurotransmitter or other chemical ligand. These channels are important for synaptic transmission and are found in the synapses between neurons.

Types of Ion Channels[edit]

Sodium channels[edit]

Sodium channels are responsible for the rapid depolarization phase of the action potential. They are highly selective for sodium ions and are blocked by tetrodotoxin.

Potassium channels[edit]

Potassium channels allow potassium ions to flow out of the cell, helping to repolarize the membrane after an action potential. They are the most diverse group of ion channels.

Calcium channels[edit]

Calcium channels are involved in a variety of cellular processes, including muscle contraction, neurotransmitter release, and gene expression.

Chloride channels[edit]

Chloride channels help maintain the resting membrane potential and regulate cell volume. They are involved in processes such as epithelial transport and neuronal excitability.

Clinical Significance[edit]

Ion channels are targets for a variety of pharmaceuticals used to treat conditions such as epilepsy, cardiac arrhythmia, and hypertension. Mutations in ion channel genes can lead to channelopathies, which are disorders caused by dysfunctional ion channels.

Related pages[edit]

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-'''Ion channels''' are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. They are often described as narrow, water-filled tunnels that allow only ions of a certain size and/or charge to pass through. This characteristic is called selective permeability. The types of ion channels include those that are directly gated by an electrical potential, ligand-gated, mechanically-gated, and thermally-gated channels.
+{{short description|Protein that allows ions to pass through it}}
+{{Use dmy dates|date=October 2023}}
-== Structure ==
+'''Ion channels''' are [[protein]]s found in the [[cell membrane]] that allow ions to pass into and out of the cell. These channels are crucial for a variety of physiological processes, including the generation of [[action potential]]s in [[neurons]], the regulation of [[heart rate]], and the release of [[hormone]]s.
-Ion channels may be composed of several different types of proteins. For example, potassium and sodium channels are known to have six transmembrane proteins. The protein subunit that forms the actual pore is called the P domain. The P domain connects the transmembrane domain with the extracellular domain. Different ion channels have different P domains.
-== Function ==
+==Structure==
-Ion channels have two main functions: they establish a resting membrane potential, and they create a change in membrane potential. The resting membrane potential is established by the concentration gradient of the ion and the ion's permeability through the membrane. Changes in the membrane potential are created by the opening and closing of ion channels. This can be due to changes in the environment, such as the binding of a ligand, a change in the voltage across the membrane, or a mechanical deformation of the channel.
+[[File:Ion_channel.png|thumb|right|Diagram of an ion channel in the cell membrane]]
+Ion channels are typically composed of multiple subunits that form a pore through which ions can pass. The structure of these channels can vary significantly, but they generally have a selectivity filter that determines which ions can pass through. The channels can be classified based on the type of ions they conduct, such as [[sodium channel]]s, [[potassium channel]]s, [[calcium channel]]s, and [[chloride channel]]s.
-== Types ==
+==Function==
-There are several types of ion channels, including voltage-gated ion channels, ligand-gated ion channels, and others. Voltage-gated ion channels open and close in response to changes in membrane potential. Ligand-gated ion channels open and close in response to specific ligand molecules binding to the channel protein.
+Ion channels play a critical role in maintaining the [[resting membrane potential]] of cells and in the propagation of [[action potential]]s. They are involved in [[signal transduction]] and are essential for the function of [[muscle]]s and [[nerve]]s. Ion channels can be gated by various stimuli, including changes in [[voltage]], binding of [[ligand]]s, or mechanical forces.
-== Clinical significance ==
+===Voltage-gated ion channels===
-Ion channels are crucial for life, and defects in ion channels can lead to a variety of diseases, known collectively as channelopathies. These include cystic fibrosis, epilepsy, and many others. Ion channels are also the target of a number of drugs, including local anesthetics, antiepileptics, and antiarrhythmics.
+[[File:Spin_1K4C.gif|thumb|left|Animation of a voltage-gated ion channel opening and closing]]
+Voltage-gated ion channels open or close in response to changes in the [[membrane potential]]. These channels are crucial for the initiation and propagation of action potentials in [[neurons]] and [[muscle cells]].
-== See also ==
+===Ligand-gated ion channels===
-* [[Voltage-gated ion channel]]
+Ligand-gated ion channels open in response to the binding of a specific [[neurotransmitter]] or other chemical [[ligand]]. These channels are important for [[synaptic transmission]] and are found in the [[synapse]]s between neurons.
-* [[Ligand-gated ion channel]]
-* [[Channelopathy]]
-== References ==
+==Types of Ion Channels==
-<references />
-[[Category:Cell biology]]
+===Sodium channels===
+Sodium channels are responsible for the rapid depolarization phase of the action potential. They are highly selective for [[sodium ion]]s and are blocked by [[tetrodotoxin]].
+===Potassium channels===
+Potassium channels allow [[potassium ion]]s to flow out of the cell, helping to repolarize the membrane after an action potential. They are the most diverse group of ion channels.
+===Calcium channels===
+Calcium channels are involved in a variety of cellular processes, including [[muscle contraction]], [[neurotransmitter release]], and [[gene expression]].
+===Chloride channels===
+Chloride channels help maintain the resting membrane potential and regulate cell volume. They are involved in processes such as [[epithelial transport]] and [[neuronal excitability]].
+==Clinical Significance==
+[[File:Birth_of_an_Idea.jpg|thumb|right|Artistic representation of ion channel research]]
+Ion channels are targets for a variety of [[pharmaceutical]]s used to treat conditions such as [[epilepsy]], [[cardiac arrhythmia]], and [[hypertension]]. Mutations in ion channel genes can lead to [[channelopathies]], which are disorders caused by dysfunctional ion channels.
+==Related pages==
+* [[Action potential]]
+* [[Neurotransmitter]]
+* [[Synapse]]
+* [[Membrane potential]]
+[[Category:Ion channels]]
 [[Category:Membrane biology]]
 [[Category:Electrophysiology]]
-[[Category:Ion channels]]
-{{stub}}