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''' | '''Ion channels''' are membrane proteins that catalyze the passive transport of ions through the cell membrane. Most ion channels are specific to an ion, like the [[natrium channels]], or the [[chloride channels]]. Some, like the [[TRP channels]], let through a bunch of cations. Another property of ion channels is that they can be either driven by voltage or concentration gradients, or they can be gated (by voltage, ligands, touch and other sensory signal). Finally, ion channels are the fastest of all membrane transporters, with 10^6 to 10^8 transported units per second versus 10^2 to 10^4 molecules per second for porters/carriers, or 10^0 to 10^3 for ATP-driven pumps. | ||
== Classification == | == Classification == | ||
TCDB, the most sophisticated classification of transport proteins to date, classify ion channels as a heterogenous subset of all α-type channels, whose singular property is to consist mainly of [[alpha helix|α-helices]] that span the membrane. They are distinct in this from the [[beta-barrel porins]], but also from non-ribosomally synthesized channels like [[gramicidin]], [[polyglutamine]] or [[digitoxin]]. | |||
== Weblinks == | == Weblinks == | ||
*[http:// | *[http://www.tcdb.org/ The TCDB database] | ||
*[http:// | *[http://www.tcdb.org/tcdb/subclass2.php?tc=1.A TCDB: 1.A α-Type channels] | ||
Revision as of 13:12, 11 February 2009
Ion channels are membrane proteins that catalyze the passive transport of ions through the cell membrane. Most ion channels are specific to an ion, like the natrium channels, or the chloride channels. Some, like the TRP channels, let through a bunch of cations. Another property of ion channels is that they can be either driven by voltage or concentration gradients, or they can be gated (by voltage, ligands, touch and other sensory signal). Finally, ion channels are the fastest of all membrane transporters, with 10^6 to 10^8 transported units per second versus 10^2 to 10^4 molecules per second for porters/carriers, or 10^0 to 10^3 for ATP-driven pumps.
ClassificationClassification
TCDB, the most sophisticated classification of transport proteins to date, classify ion channels as a heterogenous subset of all α-type channels, whose singular property is to consist mainly of α-helices that span the membrane. They are distinct in this from the beta-barrel porins, but also from non-ribosomally synthesized channels like gramicidin, polyglutamine or digitoxin.