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. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical In Vector calculus, the gradient of a Scalar field is a Vector field which points in the direction of the greatest rate of increase of the scalar The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The Membrane potential, or better Membrane Voltage, is the difference of Electric potentials between two Aqueous solutions separated by a ( An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge In Cellular biology, an electrochemical gradient is a spatial variation of both Electrical potential and chemical Concentration across a membrane They are present in the membranes that surround all biological cells. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called

Basic features

Ion channels regulate the flow of ions across the membrane in all cells. It is an integral membrane protein; or, more typically, an assembly of several proteins. An Integral Membrane Protein ( IMP) is a Protein Molecule (or assembly of proteins that is permanently attached to the Biological membrane. Such "multi-subunit" assemblies usually involve a circular arrangement of identical or homologous proteins closely packed around a water-filled pore through the plane of the membrane or lipid bilayer. In Structural biology, a protein subunit or subunit protein is a single Protein Molecule that assembles (or " coassembles " In Evolutionary biology, homology has come to mean any similarity between characters that is due to their shared ancestry. A lipid bilayer or bilayer lipid membrane ( BLM) is a membrane composed of Lipid molecules (usually Phospholipids. ^[1] The pore-forming subunit(s) are called the α subunit, while the auxiliary subunits are denoted β, γ, and so on. While some channels permit the passage of ions based solely on charge, the archetypal channel pore is just one or two atoms wide at its narrowest point. It conducts a specific species of ion, such as sodium or potassium, and conveys them through the membrane single file--nearly as quickly as the ions move through free fluid. Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 In some ion channels, passage through the pore is governed by a "gate," which may be opened or closed by chemical or electrical signals, temperature, or mechanical force, depending on the variety of channel.

Biological role

Because "voltage-gated" channels underlie the nerve impulse and because "transmitter-gated" channels mediate conduction across the synapses, channels are especially prominent components of the nervous system. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands The nervous system is a Network of specialized cells that communicate information about an animal's surroundings and itself Indeed, most of the offensive and defensive toxins that organisms have evolved for shutting down the nervous systems of predators and prey (e. g. , the venoms produced by spiders, scorpions, snakes, fish, bees, sea snails and others) work by plugging ion channel pores. In addition, ion channels figure in a wide variety of biological processes that involve rapid changes in cells, such as cardiac, skeletal, and smooth muscle contraction, epithelial transport of nutrients and ions, T-cell activation and pancreatic beta-cell insulin release. The cardiac muscle is a type of involuntary striated Muscle found in the walls of the Heart. Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Smooth muscle is a type of non- Striated muscle, found within the Tunica media layer of large and small Arteries and Veins, the bladder A muscles contraction (also known as a muscle twitch or simply twitch) occurs when a Muscle fibre generates tension through the action of Actin In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body T cells belong to a group of White blood cells known as Lymphocytes, and play a central role in Cell-mediated immunity. The pancreas is a Gland organ in the digestive and Endocrine system of Vertebrates. Insulin is a Hormone with intensive effects on both metabolism and several other body systems (eg vascular compliance In the search for new drugs, ion channels are a favorite target.

Diversity

Ion channels may be classified by the nature of their gating, the species of ions passing through those gates, and the number of gates (pores).

By gating

Ion channels may be classified by gating, i. e. what opens and closes the channels. Voltage-gated ion channels activate/inactivate depending on the voltage gradient across the plasma membrane, while ligand-gated ion channels activate/inactivate depending on binding of ligands to the channel. In Chemistry, a ligand is either an Atom, Ion, or Molecule (see also Functional group) that bonds to a central metal generally

Voltage-gated

Main article: Voltage-gated ion channel

voltage-gated channels open and close in response to membrane potential. Voltage-gated ion channels are a class of transmembrane Ion channels that are activated by changes in electrical Potential difference near the channel these Voltage-gated ion channels are a class of transmembrane Ion channels that are activated by changes in electrical Potential difference near the channel these Membrane potential (or transmembrane potential) is the Voltage difference (or Electrical potential difference between the interior and exterior of a

• Voltage-gated sodium channels: This family contains at least 9 members and is largely responsible for action potential creation and propagation. Sodium channels are Integral membrane proteins that form Ion channels, conducting sodium ions ( Na+) through a cell's Plasma membrane In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal The pore-forming α subunits are very large (up to 4,000 amino acids) and consist of four homologous repeat domains (I-IV) each comprising six transmembrane segments (S1-S6) for a total of 24 transmembrane segments. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this The members of this family also coassemble with auxiliary β subunits, each spanning the membrane once. Both α and β subunits are extensively glycosylated. Glycosylation is the enzymatic process that links Saccharides to produce glycans, either free or attached to Proteins and Lipids This enzymatic

• Voltage-gated calcium channels: This family contains 10 members, though these members are known to coassemble with α₂δ, β, and γ subunits. Voltage-dependent calcium channels (VDCC are a group of voltage-gated Ion channels found in excitable cells ( e These channels play an important role in both linking muscle excitation with contraction as well as neuronal excitation with transmitter release. The α subunits have an overall structural resemblance to those of the sodium channels and are equally large.
  • Cation channels of sperm: This small family of channels, normally referred to as Catsper channels, is related to the two-pore channels and distantly related to TRP channels. Cation channels of sperm: This small family of Ion channels normally referred to as Catsper channels or CatSper, is related to the Two-pore channels Two-pore channels This small family of 2 members putatively forms cation-selective Ion channels They are predicted to contain two KV-style six-transmembrane Transient receptor potential or TRP channels are a family of loosely related Ion channels that are non-selectively permeable to Cations including Calcium

• Voltage-gated potassium channels (K_V): This family contains almost 40 members, which are further divided into 12 subfamilies. Voltage-gated potassium channels are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's Membrane potential These channels are known mainly for their role in repolarizing the cell membrane following action potentials. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal The α subunits have six transmembrane segments, homologous to a single domain of the sodium channels. Correspondingly, they assemble as tetramers to produce a functioning channel. A tetramer is a Protein with four subunits (tetrameric There are homo-tetramers (all Subunits are identical such as Glutathione S-transferase or

• some Transient receptor potential channels: This group of channels, normally referred to simply as TRP channels, is named after their role in Drosophila phototransduction. Transient receptor potential or TRP channels are a family of loosely related Ion channels that are non-selectively permeable to Cations including Calcium Drosophila is a Genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" This family, containing at least 28 members, is incredibly diverse in its method of activation. Some TRP channels seem to be constitutively open, while others are gated by voltage, intracellular Ca²⁺, pH, redox state, osmolarity, and mechanical stretch. Voltage-gated ion channels are a class of transmembrane Ion channels that are activated by changes in electrical Potential difference near the channel these Stretch-activated or stretch-gated ion channels are Ion channels which open their Pores in response to mechanical deformation of a Neuron 's These channels also vary according to the ion(s) they pass, some being selective for Ca²⁺ while others are less selective, acting as cation channels. This family is subdivided into 6 subfamilies based on homology: classical (TRPC), vanilloid receptors (TRPV), melastatin (TRPM), polycystins (TRPP), mucolipins (TRPML), and ankyrin transmembrane protein 1 (TRPA). TRPC is a family of Transient receptor potential cation channels in animals TRPV is a family of Transient receptor potential Ion channels TRPV subunits contain three to five N-terminal Ankyrin repeats and can be activated through TRPM is a family of Transient receptor potential Ion channels where the "M" stands for "melastatin" TRPP is a family of Transient receptor potential Ion channels mutations of which are involved in Polycystic kidney disease. TRPML is a family of Transient receptor potential Ion channels The three members of the TRPML sub-family are not well characterized

• Hyperpolarization-activated cyclic nucleotide-gated channels: The opening of these channels is due to hyperpolarization rather than the depolarization required for other cyclic nucleotide-gated channels. A cyclic nucleotide-gated (CNG ion channel is any Ion channel that opens in the presence of Cyclic nucleotides Mechanism The channels are gated by Hyperpolarization any change in a cell's Membrane potential that makes it more polarized These channels are also sensitive to the cyclic nucleotides cAMP and cGMP, which alter the voltage sensitivity of the channel’s opening. These channels are permeable to the monovalent cations K⁺ and Na⁺. There are 4 members of this family, all of which form tetramers of six-transmembrane α subunits. As these channels open under hyperpolarizing conditions, they function as pacemaking channels in the heart, particularly the SA node. The contractions of the Heart are controlled by chemical impulses which fire at a rate which controls the beat of the heart The Sinoatrial node (abbreviated SA node or SAN, also called the sinus node) is the impulse generating (pacemaker tissue located in the Right atrium

• Voltage-gated proton channels: Voltage-gated proton channels openin with depolarization, but in a strongly pH-sensitive manner. The result is that these channels open only when the electrochemical gradient is outward, such that their opening will only allow protons to leave cells. Their function thus appears to be acid extrusion from cells. Another important function occurs in phagocytes (e. g. eosinophils, neutrophils, macrophages) during the "respiratory burst. Eosinophil granulocytes, usually called eosinophils (or less commonly acidophils) are White blood cells that are one of the Immune System components Neutrophil granulocytes, generally referred to as neutrophils, are the most abundant type of White blood cells in humans and form an essential part of the Macrophages ( Greek: "big eaters" from makros "large" + phagein "eat" ( Mø) are cells within the tissues that " When bacteria or other microbes are engulfed by phagocytes, the enzyme NADPH oxidase assembles in the membrane and begins to produce reactive oxygen species (ROS) that help kill bacteria. The NADPH oxidase (nicotinamide adenine dinucleotide phosphate-oxidase is a membrane-bound Enzyme complex Reactive oxygen species (ROS are ions or very small molecules that include Oxygen Ions free radicals, and Peroxides both inorganic and NADPH oxidase is electrogenic, moving electrons across the membrane, and proton channels open to allow proton flux to balance the electron movement electrically.

Ligand-gated

Main article: Ligand-gated ion channel

Ligand-gated ion channels (LGICs) activate/inactivate depending on binding of ligands to the channel. The Ligand-gated ion channels, also referred to as LGICs, or ionotropic receptors, are a group of intrinsic transmembrane ion channels that are In Chemistry, a ligand is either an Atom, Ion, or Molecule (see also Functional group) that bonds to a central metal generally

They are also known as ionotropic receptors. In Biochemistry, a receptor is a Protein molecule embedded in either the Plasma membrane or Cytoplasm of a cell to which a mobile signaling This group of channels open in response to specific ligand molecules binding to the extracellular domain of the receptor protein. Ligand binding causes a conformational change in the structure of the channel protein that ultimately leads to the opening of the channel gate and subsequent ion flux across the plasma membrane. Examples of LGICs include the cation-permeable "nicotinic" Acetylcholine receptor, ionotropic glutamate-gated receptors and ATP-gated P2X receptors, and the anion-permeable γ-aminobutyric acid-gated GABA_A receptor. An acetylcholine receptor (abbreviated AChR) is an Integral membrane protein that responds to the binding of the Neurotransmitter Acetylcholine Glutamate receptors are Transmembrane receptors located on Neuron membranes P2X receptors are a family of cation-permeable ligand gated ion channels that open in response to the binding of extracellular adenosine 5'-triphosphate ( ATP The GABA receptors are a class of receptors that respond to the Neurotransmitter γ-aminobutyric acid (GABA the chief inhibitory neurotransmitter in

Ion channels activated by may also count to this group, although ligands and second messengers otherwise are distinguished from each other.

Other gating

Other gating include activation/inactivation by e. g. second messengers from the inside of the cell membrane, rather as from outside, as in the case for ligands. In Cell physiology, a secondary messenger system (also known as a second messenger system) is a method of cellular signaling whereby a diffusable signaling molecule The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Ions may count to such second messengers, and then causes direct activation, rather than indirect, as in the case were the electric potential of ions cause activation/inactivation of voltage-gated ion channels.

• Some potassium channels
  • Inward-rectifier potassium channels: These channels allow potassium to flow into the cell in an inwardly rectifying manner, i. Inwardly rectifing potassium channels ( Kir, IRK) are a specific subset of potassium selective ion channels. e, potassium flows effectively into, but not out of, the cell. This family is composed of 15 official and 1 unofficial members and is further subdivided into 7 subfamilies based on homology. These channels are affected by intracellular ATP, PIP₂, and G-protein βγ subunits. Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy GTP chemical structurepng|thumb|180px| Guanosine triphosphate]] G proteins short for guanine nucleotide-binding proteins, are a family of Proteins involved They are involved in important physiological processes such as the pacemaker activity in the heart, insulin release, and potassium uptake in glial cells. Glial cells, commonly called neuroglia or simply glia (Greek for "glue" are non- Neuronal cells that provide support and nutrition They contain only two transmembrane segments, corresponding to the core pore-forming segments of the K_V and K_Ca channels. Their α subunits form tetramers.
  • Calcium-activated potassium channels: This family of channels is, for the most part, activated by intracellular Ca²⁺ and contains 8 members. Calcium-activated potassium channels are divided into BK channels IK channels and SK channels based on their conductance (big intermediate and small conductance
  • Two-pore-domain potassium channels: This family of 15 members form what is known as leak channels, and they follow Goldman-Hodgkin-Katz (open) rectification. Two-pore-domain potassium channels This family of 15 members form what is known as "leak channels" which possess Goldman-Hodgkin-Katz (open rectification Two-pore-domain potassium channels This family of 15 members form what is known as "leak channels" which possess Goldman-Hodgkin-Katz (open rectification The Goldman-Hodgkin-Katz current equation (or GHK current equation describes the current carried by an Ionic species across a Cell membrane as a function A rectifier is an electrical device that converts Alternating current (AC to Direct current (DC a process known as rectification.

• Light-gated channels like channelrhodopsin are directly opened by the action of light. Light-gated ion channels are a group of Transmembrane proteins that form Ion channels; pores which open or close in response to light Channelrhodopsins are Light-gated ion channels They are useful molecules enabling the use of light to control intracellular acidity calcium influx and electrical excitability

• Cyclic nucleotide-gated channels: This superfamily of channels contains two families: the cyclic nucleotide-gated (CNG) channels and the hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels. A cyclic nucleotide-gated (CNG ion channel is any Ion channel that opens in the presence of Cyclic nucleotides Mechanism The channels are gated by It should be noted that this grouping is functional rather than evolutionary.
  • Cyclic nucleotide-gated channels: This family of channels is characterized by activation due to the binding of intracellular cAMP or cGMP, with specificity varying by member. These channels are primarily permeable to monovalent cations such as K⁺ and Na⁺. They are also permeable to Ca²⁺, though it acts to close them. There are 6 members of this family, which is divided into 2 subfamilies.
  • Hyperpolarization-activated cyclic nucleotide-gated channels

By ions

• Chloride channels: This superfamily of poorly understood channels consists of approximately 13 members. A cyclic nucleotide-gated (CNG ion channel is any Ion channel that opens in the presence of Cyclic nucleotides Mechanism The channels are gated by Chloride channels are a superfamily of poorly understood Ion channels consisting of approximately 13 members

• Potassium channels
  • Voltage-gated potassium channels
  • Calcium-activated potassium channels
  • Inward-rectifier potassium channels
  • Two-pore-domain potassium channels: This family of 15 members form what is known as leak channels, and they follow Goldman-Hodgkin-Katz (open) rectification. In the field of Cell biology, potassium channels are the most widely distributed type of Ion channel and are found in virtually all living organisms Voltage-gated potassium channels are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's Membrane potential Calcium-activated potassium channels are divided into BK channels IK channels and SK channels based on their conductance (big intermediate and small conductance Inwardly rectifing potassium channels ( Kir, IRK) are a specific subset of potassium selective ion channels. Two-pore-domain potassium channels This family of 15 members form what is known as "leak channels" which possess Goldman-Hodgkin-Katz (open rectification Two-pore-domain potassium channels This family of 15 members form what is known as "leak channels" which possess Goldman-Hodgkin-Katz (open rectification The Goldman-Hodgkin-Katz current equation (or GHK current equation describes the current carried by an Ionic species across a Cell membrane as a function A rectifier is an electrical device that converts Alternating current (AC to Direct current (DC a process known as rectification.

• Sodium channels

• Calcium channels

• Proton channels
  • Voltage-gated proton channels

• General ion channels: These are relatively non-specific for ions and thus let many types of ions through the channel. Sodium channels are Integral membrane proteins that form Ion channels, conducting sodium ions ( Na+) through a cell's Plasma membrane A Calcium channel is an Ion channel which displays selective permeabiltiy to Calcium ions
  • Most Transient receptor potential channels

Other classifications

There are other types of ion channel classifications that are based on less normal characteristics, e. Transient receptor potential or TRP channels are a family of loosely related Ion channels that are non-selectively permeable to Cations including Calcium g. multiple pores and transient potentials.

Almost all ion channels have one single pore. However, there are also those with two:

• Two-pore channels: This small family of 2 members putatively forms cation-selective ion channels. Two-pore channels This small family of 2 members putatively forms cation-selective Ion channels They are predicted to contain two KV-style six-transmembrane They are predicted to contain two K_V-style six-transmembrane domains, suggesting they form a dimer in the membrane. These channels are related to catsper channels channels and, more distantly, TRP channels. Cation channels of sperm: This small family of Ion channels normally referred to as Catsper channels or CatSper, is related to the Two-pore channels Transient receptor potential or TRP channels are a family of loosely related Ion channels that are non-selectively permeable to Cations including Calcium

Most ion channels make a relatively long-lasting potential change. However, there are also channels that only make a transient one:

• Transient receptor potential channels: This group of channels, normally referred to simply as TRP channels, is named after their role in Drosophila phototransduction. Transient receptor potential or TRP channels are a family of loosely related Ion channels that are non-selectively permeable to Cations including Calcium Drosophila is a Genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" This family, containing at least 28 members, is incredibly diverse in its method of activation. Some TRP channels seem to be constitutively open, while others are gated by voltage, intracellular Ca²⁺, pH, redox state, osmolarity, and mechanical stretch. Voltage-gated ion channels are a class of transmembrane Ion channels that are activated by changes in electrical Potential difference near the channel these Stretch-activated or stretch-gated ion channels are Ion channels which open their Pores in response to mechanical deformation of a Neuron 's These channels also vary according to the ion(s) they pass, some being selective for Ca²⁺ while others are less selective, acting as cation channels. This family is subdivided into 6 subfamilies based on homology: cannonical (TRPC), vanilloid receptors (TRPV), melastatin (TRPM), polycystins (TRPP), mucolipins (TRPML), and ankyrin transmembrane protein 1 (TRPA). TRPC is a family of Transient receptor potential cation channels in animals TRPV is a family of Transient receptor potential Ion channels TRPV subunits contain three to five N-terminal Ankyrin repeats and can be activated through TRPM is a family of Transient receptor potential Ion channels where the "M" stands for "melastatin" TRPP is a family of Transient receptor potential Ion channels mutations of which are involved in Polycystic kidney disease. TRPML is a family of Transient receptor potential Ion channels The three members of the TRPML sub-family are not well characterized

Detailed structure

Channels differ with respect to the ion they let pass (for example, Na⁺, K⁺, Cl⁻), the ways in which they may be regulated, the number of subunits of which they are composed and other aspects of structure. Channels belonging to the largest class, which includes the voltage-gated channels that underlie the nerve impulse, consists of four subunits with six transmembrane helices each. Transmembrane domain usually denotes a single transmembrane Alpha helix of a Transmembrane protein. On activation, these helices move about and open the pore. Two of these six helices are separated by a loop that lines the pore and is the primary determinant of ion selectivity and conductance in this channel class and some others. The existence and mechanism for ion selectivity was first postulated in the 1960s by Clay Armstrong. Clay Armstrong is a prominent physiologist and a former student of Dr The channel subunits of one such other class, for example, consist of just this "P" loop and two transmembrane helices. The determination of their molecular structure by Roderick MacKinnon using X-ray crystallography won a share of the 2003 Nobel Prize in Chemistry. Roderick MacKinnon (born 19 February 1956) is a professor of Molecular Neurobiology and Biophysics at Rockefeller University who won the Crystallography is the experimental science of determining the arrangement of Atoms in Solids In older usage it is the scientific study of Crystals The The Nobel Prize in Chemistry (Nobelpriset i kemi is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of Chemistry.

Because of their small size and the difficulty of crystallizing integral membrane proteins for X-ray analysis, it is only very recently that scientists have been able to directly examine what channels "look like. " Particularly in cases where the crystallography required removing channels from their membranes with detergent, many researchers regard images that have been obtained as tentative. An example is the long-awaited crystal structure of a voltage-gated potassium channel, which was reported in May 2003. The detailed 3D structure of the magnesium channel from bacteria can be seen here. One inevitable ambiguity about these structures relates to the strong evidence that channels change conformation as they operate (they open and close, for example), such that the structure in the crystal could represent any one of these operational states. Most of what researchers have deduced about channel operation so far they have established through electrophysiology, biochemistry, gene sequence comparison and mutagenesis. Electrophysiology (from Greek grc ἥλεκτρον ēlektron, "amber" the [[Electron#Etymology|etymology of "electron"]] grc φύσις Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance A process by which the genetic information of an Organism is changed in a stable manner either in nature or experimentally by the use of Chemicals or Radiation.

Diseases of Ion Channels

There are a number of chemicals and genetic disorders which disrupt normal functioning of ion channels and have disastrous consequences for the organism. Genetic disorders of ion channels and their modifiers are known as Channelopathies. Channelopathies are diseases caused by disturbed function of Ion channel subunits or the Proteins that regulate them See Category:Channelopathy for a full list.

Chemicals

• Tetrodotoxin (TTX), used by puffer fish and some types of newts for defense. Tetrodotoxin (anhydrotetrodotoxin 4-epitetrodotoxin tetrodonic acid TTX is a potent Neurotoxin with no known antidote which blocks Action potentials in Nerves Tetraodontidae is a family of primarily marine and estuarine fish A newt is an Amphibian of the Salamandridae family order Urodela or Caudata, found in North America, Europe, and It is a sodium channel blocker.
• Saxitoxin, produced by a dinoflagellate also known as "red tide". Saxitoxin ( STX) is a neurotoxin naturally produced by certain species of marine Dinoflagellates ( Alexandrium sp The dinoflagellates are a large group of Flagellate Protists Most are marine Plankton, but "Red tide" is a common name for a phenomenon known as an Algal bloom, an event in which estuarine marine or fresh water algae accumulate rapidly in the Water It blocks voltage dependent sodium channels.
• Conotoxin, which is used by cone snails to hunt prey. A conotoxin is one of a group of neurotoxic Peptides isolated from the venom of the marine Cone snail, genus Conus. The cone snails or cone shells, sometimes simply known as "cones" (family Conidae) are a Taxonomic family of medium-sized to large sophisticated
• Lidocaine and Novocaine belong to a class of local anesthetics which block sodium ion channels. Lidocaine ( INN) (ˈlaɪdoʊkeɪn or lignocaine (former BAN) (/ˈlɪgnoʊkeɪn/ is a common Local anesthetic and antiarrhythmic drug Procaine is a Local anesthetic drug of the Amino Ester group It is used primarily to reduce the pain of Intramuscular injection of A local anesthetic is a drug that causes reversible Local anesthesia and a loss of Nociception.
• Dendrotoxin is produced by mamba snakes which blocks potassium channels. Dendrotoxins are a class of Neurotoxins produced by Mamba Snakes ( Dendroapsis) that block particular subtypes of Voltage-gated MAMBA stands for Mobile Artillery Monitoring Battlefield Asset, a Counter-battery radar operated by the Royal Artillery. A snake is an elongate Reptile of the suborder Serpentes Like all reptiles snakes are covered in scales.
• Iberiotoxin is produced by the Buthus tamulus which blocks potassium channels. Chemistry Iberiotoxin is a 37- Amino acid Peptide. It is also known as "Potassium channel toxin alpha-KTx 1
• heteropodatoxin is produced by Heteropoda venatoria which blocks potassium channels. Heteropodatoxins are Peptide toxins from the venom of the giant crab spider Heteropoda venatoria, which block Kv4

Genetic

• Shaker gene mutations cause a defect in the voltage gated ion channels, slowing down the repolarization of the cell. The Shaker (Sh gene when mutated causes a variety of atypical behaviors in the fruit fly, Drosophila melanogaster.
• Equine hyperkalaemic periodic paralysis as well as Human hyperkalaemic periodic paralysis (HyperPP) are caused by a defect in voltage dependent sodium channels. Hyperkalaemic periodic paralysis is a Genetic disorder which occurs in both humans and horses Hyperkalaemic periodic paralysis is a Genetic disorder which occurs in both humans and horses
• Paramyotonia congenita (PC) and potassium aggravated myotonias (PAM)
• Generalized epilepsy with febrile seizures plus (GEFS+)
• Episodic Ataxia (EA), characterized by sporadic bouts of severe discoordination with or without myokymia, and can be provoked by stress, startle, or heavy exertion such as exercise. Paramyotonia Congenita (PC also known as Paramyotonia congenita of von Eulenburg or Eulenburg disease, is a rare congenital Autosomal dominant neuromuscular Generalized epilepsy with febrile seizures plus (GEFS+ is a syndromic Autosomal dominant disorder where afflicted individuals can exhibit numerous Epilepsy Episodic ataxia (EA is an Autosomal dominant disorder characterized by sporadic bouts of Ataxia (severe discoordination with or without myokymia (continuous muscle
• Familial hemiplegic migraine (FHM)
• spinocerebellar ataxia type 13
• Long QT syndrome is a ventricular arrhythmia syndrome caused by mutations in one or more of presently ten different genes, most of which are potassium channels and all of which affect cardiac repolarization. Familial hemiplegic migraine (FHM is an Autosomal dominant classical Migraine subtype that typically includes Hemiparesis (weakness of half the body during The long QT syndrome ( LQTS) is a Heart condition associated with prolongation of repolarization (recovery following depolarization (excitation of the cardiac In the Heart, a ventricle is a heart chamber which collects Blood from an atrium (another heart chamber that is smaller than a ventricle and Dysrhythmia redirects here For the American band see Dysrhythmia (band. In Medicine and Psychology, the term syndrome refers to the association of several clinically recognizable features signs (observed by a physician In biology mutations are changes to the Nucleotide sequence of the Genetic material of an organism History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance In the field of Cell biology, potassium channels are the most widely distributed type of Ion channel and are found in virtually all living organisms In Neuroscience, repolarization refers to the change in Membrane potential that returns the membrane potential to a negative value after the Depolarization
• Brugada syndrome is another ventricular arrhythmia caused by voltage-gated sodium channel gene mutations. The Brugada syndrome is a Genetic disease that is characterised by abnormal Electrocardiogram (ECG findings and an increased risk of Sudden cardiac death Sodium channels are Integral membrane proteins that form Ion channels, conducting sodium ions ( Na+) through a cell's Plasma membrane
• Cystic fibrosis is caused by mutations in the CFTR gene, which is a chloride channel. Cystic fibrosis (also known as CF, mucoviscoidosis, or mucoviscidosis) is a hereditary disease affecting the exocrine (mucus glands of the lungs

History

The existence of ion channels was hypothesized by the British biophysicists Alan Hodgkin and Andrew Huxley as part of their Nobel Prize-winning theory of the nerve impulse, published in 1952. Biophysics (also biological physics) is an Interdisciplinary Science that employs and develops theories and methods of the Physical sciences for Sir Alan Lloyd Hodgkin, OM, KBE, FRS (5 February 1914 Banbury, Oxfordshire, England – 20 December 1998 Cambridge Sir Andrew Fielding Huxley, OM, FRS (born 22 November 1917, Hampstead, London) is an English physiologist The Nobel Prize in Physiology or Medicine (Nobelpriset i fysiologi eller medicin is awarded once a year by the Swedish Karolinska Institute. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal The existence of ion channels was confirmed in the 1970s with an electrical recording technique known as the "patch clamp," which led to a Nobel Prize to Erwin Neher and Bert Sakmann, the technique's inventors. This article is about the Decade 1970-1979 For the Year 1970 see 1970. Electrophysiology (from Greek grc ἥλεκτρον ēlektron, "amber" the [[Electron#Etymology|etymology of "electron"]] grc φύσις The patch clamp technique is a Laboratory technique in Electrophysiology that allows the study of single or multiple Ion channels in cells Erwin Neher (born March 20, 1944 in Landsberg am Lech, Bavaria) is a German biophysicist. Bert Sakmann (born June 12, 1942) is a German cell Physiologist. Hundreds if not thousands of researchers continue to pursue a more detailed understanding of how these proteins work. In recent years the development of automated patch clamp devices helped to increase the throughput in ion channel screening significantly. Electrophysiology (from Greek grc ἥλεκτρον ēlektron, "amber" the [[Electron#Etymology|etymology of "electron"]] grc φύσις

The Nobel Prize in Chemistry for 2003 was awarded to two American scientists: Roderick MacKinnon for his studies on the physico-chemical properties of ion channel function, including x-ray crystallographic structure studies and Peter Agre for his similar work on aquaporins. Roderick MacKinnon (born 19 February 1956) is a professor of Molecular Neurobiology and Biophysics at Rockefeller University who won the X-ray crystallography is a method of determining the arrangement of Atoms within a Crystal, in which a beam of X-rays strikes a crystal and scatters Proteins are an important class of biological Macromolecules present in all biological organisms made up of such elements as Carbon, Hydrogen Peter Agre (born January 30, 1949) is an American medical doctor professor and molecular biologist who was awarded the 2003 Nobel Prize in Chemistry Aquaporins are Integral membrane proteins from a larger family of Major intrinsic proteins (MIP that form Pores in the membrane

Reference:

• Nobel Prize Press Release

The Ion Channel in Fine Art

Birth of an Idea (2007) by Julian Voss-Andreae. The sculpture was commissioned by Roderick MacKinnon based on the molecule's atom coordinates that where deposited by MacKinnon's group in 2001. Roderick MacKinnon (born 19 February 1956) is a professor of Molecular Neurobiology and Biophysics at Rockefeller University who won the

Roderick MacKinnon commissioned "Birth of an Idea", a 5' (1. Roderick MacKinnon (born 19 February 1956) is a professor of Molecular Neurobiology and Biophysics at Rockefeller University who won the 50 m) tall sculpture based on the KcsA potassium channel. The artwork contains a wire object representing the pore liner with a blown glass object representing the main cavity of the channel structure.

References

1. ^ Two textbooks that discuss ion channels are: Neuroscience (2nd edition) Dale Purves, George J. Augustine, David Fitzpatrick, Lawrence. C. Katz, Anthony-Samuel LaMantia, James O. McNamara, S. Mark Williams, editors. Published by Sinauer Associates, Inc. (2001) online textbook and Basic Neurochemistry: Molecular, Cellular, and Medical Aspects (6th edition) by George J Siegel, Bernard W Agranoff, R. W Albers, Stephen K Fisher and Michael D Uhler published by Lippincott, Williams & Wilkins (1999): online textbook

• Bertil Hille Ion channels of excitable membranes, 3rd ed. Dr Bertil Hille is an American biologist He has been on the faculty of the Department of Physiology and Biophysics at the University of Washington since 1968 , Sinauer Associates, Sunderland, MA (2001). ISBN 0-87893-321-2
• International Union of Pharmacologists, Ion channel compendium

See also

• Action potential
• Active transport
• Channelopathy
• Neurotoxin
• Magnesium transport
• Passive transport
• Transmembrane receptor
• Wikipedia:MeSH D12.776#MeSH D12.776.543.550.425 --- ion channels
• K_i Database
• Ion channel family as defined in Pfam and InterPro

External links

• An Interview with Roderick MacKinnon Freeview video by the Vega Science Trust. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal Active transport is the mediated process of moving particles across Biological membrane against the concentration gradient Channelopathies are diseases caused by disturbed function of Ion channel subunits or the Proteins that regulate them A neurotoxin is a Toxin that acts specifically on nerve cells ( Neurons, usually by interacting with Membrane proteins such as Ion channels This page links directly from the Magnesium in biological systems page Passive transport means moving biochemicals and atomic or molecular substances across the Cell membrane. Transmembrane receptors are Integral membrane proteins which reside and operate typically within a cell's Plasma membrane, but also in the membranes of The Ki Database (or Ki DB) is a Public domain Database of published binding affinities ( K i of Transmembrane ion channel family was defined in InterPro and Pfam as the family of tetrameric sodium, potassium, and Pfam is a large collection of Multiple sequence alignment and Hidden Markov models covering many common protein domains and families InterPro is a database of protein families domains and functional sites in which identifiable features found in known proteins can be applied to new protein sequences
• The Voltage Sensor in Voltage-Dependent Ion Channels
• X-ray crystal structure of a potassium channel
• Neuromuscular Disease Center at Washington University