Nutrition Guide

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.

Ligand-gated ion channels (LGICs), also referred to as ionotropic receptors or channel-linked receptors, are a group of transmembrane ion channels that are opened or closed in response to the binding of a chemical messenger (i.e., a ligand),[1] such as a neurotransmitter.[2] The direct link to an ion channel, which is characteristic of ligand-gated ion channels, is contrasted with the indirect function of metabotropic receptors, which use second messengers. Ligand-gated ion channels are also different from voltage-gated ion channels (which open and close depending on membrane potential), and stretch-activated ion channels (which open and close depending on mechanical deformation of the cell

Such channels are of use in the initial formation of an action potential from a mechanical stimulus, for example by the mechanoreceptors in an animal's vibrissae (whiskers). A possible role in myoblast development has been described.[2]

Other types of gated ion channels, ligand-gated and voltage-gated, have been synthesized with a light-gated component in an attempt to better understand their nature and properties. By the addition of a light-gated section, the kinetics and mechanisms of operation can be studied in depth. For example, the addition of a light-gated component allows for the introduction of many highly similar ligands to be introduced to the binding site of a ligand-gated ion channel to assist in the determination of the mechanism. In 1980, the first ion channel to be adapted for study with a light-gated mechanism was the nicotinic acetylcholine receptor.[2]

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. They have a crucial role in excitable neuronal and muscle tissues, allowing a rapid and co-ordinated depolarisation in response to triggering voltage change. Found along the axon and at the synapse, voltage-gated ion channels directionally propagate electrical signals.

Chloride channel CLIC-like 1 also known as CLCC1 is a human gene.[1][2] The protein encoded by this gene is a chloride channel which is related in sequence to the S. cerevisiae MID-1 stretch-activated channel. CLCC1 is located in the membranes of intracellular compartments including endoplasmic reticulum and the Golgi apparatus. It is highly expressed in the testis and moderately in the spleen, liver, kidney, heart, brain, and lung.[2]

Channel blockers are chemical substances, ranging from ions to complex organic molecules, that bind inside the pore of an ion channel and block the flow of ions through that channel. A subset of channel blockers, known as "open channel blockers" have access to their intra-channel binding site only when the channel is in the open configuration (i.e. in the configuration that conducts transmembrane ion flux). Open channel block is characterized by "flickery closings" in single-channel recordings.

Mechanosensitive ion channels (MscL) play a critical role in transducing physical stresses at the cell membrane into an electrochemical response.[1] MscL forms a channel organized as a homopentamer, with each subunit containing two transmembrane ?-helices. Prokaryotes harbor a large-conductance mechanosensitive channel (gene mscL) that opens in response to stretch forces in the lipid bilayer and participate in the regulation of osmotic pressure within the cell.[2]

Potassium channel, subfamily K, member 4, also known as KCNK4, is a human gene.[1] Potassium channels play a role in many cellular processes including maintenance of the action potential, muscle contraction, hormone secretion, osmotic regulation, and ion flow. This gene encodes K2P4.1, one of the members of the superfamily of potassium channel proteins containing two pore-forming P domains. K2P4.1 homodimerizes and functions as an outwardly rectifying channel. It is expressed primarily in neural tissues and is stimulated by membrane stretch and polyunsaturated fatty acids.

Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 2, also known as KCNN2, is a human gene encoding the ion channel protein KCa2.2.[1] Action potentials in vertebrate neurons are followed by an afterhyperpolarization (AHP) that may persist for several seconds and may have profound consequences for the firing pattern of the neuron. Each component of the AHP is kinetically distinct and is mediated by different calcium-activated potassium channels. The KCa2.2 protein is activated before membrane hyperpolarization and is thought to regulate neuronal excitability by contributing to the slow component of synaptic AHP. KCa2.2 is an integral membrane protein that forms a

Transmembrane ion channel family was defined in InterPro and Pfam as the family of tetrameric sodium, potassium, and calcium ion channels, in which two C-terminal transmembrane helices flank a loop which determines ion selectivity of the channel pore. This large group of ion channels apparently includes families 1.A.1, 1.A.2, 1.A.3, and 1.A.4 of transporter classification. Many eukariotic channels have four additional transmembrane helices (TMH) (Pfam PF00520), whereas a bacterial structure of the protein has only two transmembrane helices that form the tetrameric channel (Pfam PF07885).

Roderick MacKinnon commissioned "Birth of an Idea", a 5' (1.50 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.

SK channels (Small conductance calcium-activated K (potassium) channels) are a subfamily of Ca2+-activated K+ channels.[1] SK channels are a type of ion channel allowing potassium cations to cross the cell membrane and are activated (opened) by an increase in the concentration of intracellular calcium. Their activation limits the firing frequency of action potentials and are important for regulating afterhyperpolarization in central neurons and other types of electrically excitable cells.[2] SK channels are thought to be involved in synaptic plasticity and therefore play important roles in memory and learning.

Calcium-activated potassium channels are divided into BK channels, IK channels, and SK channels based on their conductance (big, intermediate, and small conductance). This family of ion channels is, for the most part, activated by intracellular Ca2+ and contains 8 members. It should be noted, however, that some of these channels (the KCa4 and KCa5 channels) are responsive instead to intracellular Na+ and Cl-. Furthermore, the KCa1 family is both Ca2+ and voltage activated, further complicating the description of this family. The KCa channel ? subunits have six transmembrane segments similar to the KVs, except KCa1, in which the N-terminus makes a

There are other types of ion channel classifications that are based on less normal characteristics, e.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. They are predicted to contain two KV-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. There are channels that are classified by the duration of the response to stimuli: Transient receptor potential channels: This group of channels, normally referred to

Leave a Reply

Name (required)

Mail (will not be published) (required)

Website