aquaporin


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channel

 [chan´el]
a passage, cut, or groove through which something can pass or flow across a solid structure.
calcium channel (calcium-sodium channel) a slow voltage-gated channel very permeable to calcium ions and slightly permeable to sodium ions, existing in three subtypes designated L, M, and N and located throughout the body; calcium channels are the main cause of action potentials in certain smooth muscles, and the N channels regulate neurotransmitter release.
fast channel a protein channel, such as a sodium channel, that becomes activated relatively quickly; a fast voltage-gated channel has a much lower activation potential than does the slow type. See also slow channel.
ligand-gated channel a protein channel that opens in response to the binding of a molecule (the ligand) to the protein, which causes a conformational change in the protein molecule. See also voltage-gated channel.
potassium channel a slow voltage-gated channel selective for the passage of potassium ions, found on the surface of a wide variety of cells, including nerve, muscle, and secretory cells; its functions include regulation of cell membrane excitability, regulation of repetitive low frequency firing in some neurons, and recovery of the nerve fiber membrane at the end of the action potential.
protein channel a watery pathway through the interstices of a protein molecule by which ions and small molecules can cross a membrane into or out of a cell by diffusion; protein channels play a vital role in depolarization and repolarization of nerve and muscle fibers, and may have physical characteristics such as shape or diameter that particularly attract certain ions.
slow channel a protein channel such as the calcium channel that is slow to become activated; a slow voltage-gated channel has a much higher activation potential than does the fast type. See also fast channel.
sodium channel a type of fast channel selective for the passage of sodium ions. Voltage-gated sodium channels are the main causes of depolarization and repolarization of nerve membranes during the action potential. In cardiac cells they produce phase 0 of the action potential.
voltage-gated channel a protein channel that can be opened or closed in response to changes in the electric potential across a cell membrane. See also ligand-gated channel.
water channel a channel in a cell membrane that permits passage of water molecules; chemical substances such as vasopressin cause the opening of new channels and increase permeability.

aquaporin

(ak-kwă-pōr'in),
A member of a family of transmembrane channel proteins found in epithelial membranes that serve to regulate transepithelial water movement in tissues involved in body fluid homeostasis.
[L aqua, water, + porus, channel, pore, + -in]

aquaporin

[ak′wah-po′rin]
any of a family of proteins found in plasma membranes and forming a functional component of water channels.

aquaporin

(ak″wă-por′ĭn) [ aqua + porin]
A cell membrane protein that lets water flow into and out of cells.
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References in periodicals archive ?
Unexpected complexity of the aquaporin gene family in the moss Physcomitrella patens.
of aquaporins can be regulated in response to intracellular pH.
ficiformis we identified a transcript putatively coding for an unorthodox aquaporin (Aqp12L): it is the first report of this kind of channel to be found in Porifera, but it is to be expected with the expansion of transcriptomic data from this animal lineage, and is surely worth further investigation.
Aquaporin molecular characterization in the sea-bass (Dicentrarchus labrax): the effect of salinity on AQPI and AQP3 expression.
Aquaporin 1 is mainly expressed in the apical pole of the choroid plexus epithelial cells.
ANF, ANCA, RF, RPR, human T lymphotropic virus 1, CSF OB and aquaporin 4 antibodies were negative.
Homology modeling approaches were used to study the conformational changes between the holo and apo physiological states of the ATP-binding cassette (ABC) superfamily of proteins [6,7] and for characterizing the water and glicerol permeability and response to drug inhibitors of aquaporins [8,9], an argument clearly related to drug design.
Other inner elements also contribute to maintain water levels and hydration, such as the aquaporin family that facilitates the transport of water molecules and its flux, avoiding water shortage in needed zones.
Using high throughput DNA sequencing methods they were able to pin down the underlying cause of the condition to mutations in the AQP5 gene, which encodes a water channel protein known as aquaporin 5.
In order to study the process he and his colleagues used living cells which expressed the "fluorescent" protein GFP, attached to the aquaporin AQP9.