Ion channels

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 sodium channels, or the chloride channels. Some, like the TRP channels, let through various 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). Potassium channels (KCh) are subdivided to voltage-gated KCh and calcium-dependent KCh. The latter are subdivided into high- (BK, LKCa), intermediate- and small-conductance KCh (human SK1, rat SK2, SKCa). MthK is a calcium-dependent potassium channel from Methanobacterium thermoautrophicum. MscL and MscS are large- and small-conductance mechanosensitive channels which protect bacteria from osmotic shock by allowing ions to flow across the cell membrane Mechanosensitive channels: opening and closing. Voltage-Dependent Calcium Channels (VDCC) allow Ca⁺⁺ to enter the cell resulting in muscle contraction, neuron excitation or hormone release. VDCC are composed of several subunits and are named as a Cav gene product. Finally, ion channels are the fastest of all membrane transporters, with 10⁶ to 10⁸ transported units per second versus 10² to 10⁴ molecules per second for porters/carriers, or 10⁰ to 10³ for ATP-driven pumps. Specific details in:

• Proton Channels,
  
• Membrane Channels & Pumps,
  
• M2 Proton Channel,
  
• M2 Proton Channel Inhibitor Pharmacokinetics,
  
• User:Michael Strong/H1N1/MP give details on proton channels,
  
• User:Michael Strong/H1N1/MP1/MSA,
  
• User:Michael Strong/H1N1/MP2/MSA for multiple sequence alignment
  
• Chloride Ion Channel
  
• User:Laura Fountain/Chloride Ion Channel
  
• Chloride Intracellular Channel Protein 2
  
• Mechanosensitive channels: opening and closing
  
• Voltage-gated calcium channels
  
• Ryanodine receptor.
  
• Hypertension & Congestive Heart Failure.

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 and the pore-forming toxins, as well as from non-ribosomally synthesized channels like gramicidin, polyglutamine or digitoxin. All these proteins are passive transport proteins.

Additional ResourcesAdditional Resources

For additional information, see: Membrane Channels & Pumps
For additional information, see: Hypertension & Congestive Heart Failure

Available 3D structuresAvailable 3D structures

Ion channels translate ionic fluxes across cell membrane into electrical impulses. MscL and MscS are large- and small-conductance mechanosensitive channels which protect bacteria from osmotic shock by allowing ions to flow across the cell membrane. Voltage-Dependent Calcium Channels (VDCC) allow Ca+2 ions to enter the cell resulting in muscle contraction, neuron excitation or hormone release. VDCC are composed of several subunits and are named as a Cav gene product. The human annexin V molecule serves as a calcium channel. There are also Voltage-Dependent Anion Channels (VDAC). Chloride ion channels (ClCh) are involved in maintaining pH, volume homeostasis and more. Ligand-Gated Ion Channels (LGIC) open or close when binding a ligand like a neurotransmitter. The Cyclic Nucleotide-Gated channels (CNGC) conduct cations upon binding of cAMP or cGMP. The Acid-Sensitive channels (ASC) conduct cations upon binding of acid. The glycerol facilitator (GlpF) is a protein channel which transports glycerol across the cell membrane of E. coli. Other ion channel proteins are the aquaporins, gramicidin, antiamoebin, trichotoxin, peptaibol and the glutamate receptor.

Updated on 10-February-2016

{"openlevels":0}

• Potassium channel See: Potassium Channels
• Calcium channel
  • 3bxx – rCav2.1 α 1A subunit+calmodulin - rabbit
    
  • 3bxl - rCav2.3 α 1E subunit+calmodulin
    
  • 2f3y, 2f3z, 2be6 – hCav1.2 α 1C subunit+calmodulin - human
    
  • 1t0h – rVDCC β 2A subunit
    
  • 1t0j – rVDCC β 2A+α 1C
    
  • 1vyt - rVDCC β 3+α 1C
    
  • 1vyu – rVDCC β 3
    
  • 1vyv - rVDCC β 4
    
  • 1t3l - rVDCC β 2+α 1S
    
  • 1t3s - rVDCC β 2
    
  • 2d46 – hVDCC β 4a – NMR
    
  • 3dve, 3dvj, 3dvk, 3dvm, 3g43 - rCav2.2 α 1B subunit+hCalmodulin
    
  • 4dex - rCav2.2 α 1B + β 2 subunits
    
  • 4dey - rCav2.2 α 1C + β 2 subunits
    
  • 3oxq - hCav2.1 α 1C subunit IQ domain+hCalmodulin
    
  • 2vay, 3oxq - hCav1.1 α 1S subunit IQ domain+hCalmodulin
    
  • 1hvd, 1hve, 1hvf, 1hvg – hAnnexin V (mutant)
    
• See also Ryanodine receptor
• Sodium channel
  • 1byy - rNaCh IIA inactivation fragment
    
  • 2kav, 2kbi - hNaV 1.2 α C-terminal EF-hand domain - NMR
    
  • 4l1d - hNaV β 3 IG domain
    
  • 4mz2 - hNaV β 4 extracellular domain
    
  • 4mz3 - hNaV β 4 extracellular domain (mutant)
    
  • 4ovn – hNaV 1.5 α C terminal + calmodulin
    
  • 4dck, 4jq0 – hNaV 1.5 α C terminal + calmodulin + fibroblast growth factor
    
  • 4jpz – hNaV 1.2 α C terminal + calmodulin + fibroblast growth factor 13
    
  • 1qg9 – NaCh IIA second repeat – rat – NMR
    
  • 4bgn – NaCh – Caldalkalibacillus thermarum – Cryo EM
    
  • 4lto, 4ltp, 4ltq – AeNaCh pore + cytoplasmic domains – Alkalilimnicola ehrlichii
    
  • 4ltr – AeNaCh pore + cytoplasmic domains (mutant)
    
• NH4+ channel
  • 2nmr, 2nop, 2now, 2npc, 2npd, 2npe, 2npj, 2npg, 2npk, 1u77, 1u7c, 1u7g, 1xqe, 1xqf, 3c1g – EcAmCh – Escherichia coli
    
  • 3c1h, 3c1i, 3c1j – EcAmCh (mutant)
    
  • 4nh2 – EcAmCh + phosphatidylglycerol
    
  • 2ns1, 2nuu – EcAmCh + nitrogen regulatory protein
    
  • 2b2h, 2b2i, 2b2j, 2b2f – AmCh – Archaeglobus fulgidus
    
  • 3b9w, 3b9y, 3bhs – AmCh – Nitrosomonas europaea
• MscL and MscS
  • 3hzq – MscL – Staphylococcus aureus
    
  • 2oar – MscL – Mycobacterium tuberculosis
    
  • 4lku – EcMscL C terminal
    
  • 2oau, 2vv5, 4hwa - EcMscS
    
  • 4age, 4agf – EcMscS (mutant)
    
  • 3t9n, 3udc – MscS – Thermoanaerobacter tengcongensis
    
• Chloride channel
  • 1rk4, 3swl - hClCh protein 1
    
  • 3o3t, 3p8w, 3p90, 1k0o, 3qr6, 3tgz, 1k0m, 3uvh, 4iqa, 4jzq, 4k0g, 4k0n - hClCh protein 1 (mutant)
    
  • 1k0n - hClCh protein 1 (mutant) + glutathione
    
  • 2per, 2r4v, 2r5g - hClCh protein 2
    
  • 3kjy, 3fy7 - hClCh protein 3 residues 1-230
    
  • 2ahe, 2d2z – hClCh protein 4
    
  • 2pfi - hClCh KA
    
  • 2j9l, 2ja3 - hClCh protein 5 + nucleotide
    
  • 1ots - EcERIC + antibody
    
  • 1ott, 1otu - EcERIC (mutant) + antibody
    
  • 2d4z - TmClCh - Torpedo marmorata
    
  • 2yv9 - ClCh EXC-4 – Caenorhabditis elegans
    
• Anion Channel (Outer mitochondrial membrane protein porin 1)
  • 2jk4, 2k4t – hVDAC1
    
  • 3emn, 4c69 – mVDAC1 - mouse
    
  • 4bum – zeVDAC2 – zebra fish
    
• Ligand-gated ion channel
  • 2vl0, 2yn6, 3rqu – EchLGIC – Erwinia chrysanthemi
    
  • 2yks, 4twh - EchLGIC (mutant)
    
  • 2xq3, 2xq4, 2xq5, 2xq6, 2xq7, 2xqa, 2xq8 – GvLGIC+inhibitor – Gloeobacter violaceus
    
  • 3eam, 3ehz, 4hfi, 4il4, 4ilc, 4npp, 4npq, 4qh1, 4qh5 – GvLGIC
    
  • 3igq – GvLGIC N-terminal
    
  • 2xq9 – GvLGIC (mutant)+inhibitor
    
  • 3p4w, 3p50, 4f8h, 4hfh – GvLGIC + general anaesthetic
    
  • 4hfd – GvLGIC (mutant) + general anaesthetic
    
  • 4hfc, 4hfe - GvLGIC (mutant) + alcohol
    
  • 3lsv, 3tls, 3tlt, 3tlu, 3tlv, 3tlw, 3uu3, 3uu4, 3uu5, 3uu6, 3uu8, 3uub, 3ei0, 4hfb, 4il9, 4ila, 4ilb, 4ire, 4lmj, 4lmk, 4lml – GvLGIC (mutant)
    
  • 3rqw - EchElic + acetylcholine
    
  • 4twd, 4twf - EchElic (mutant) + memantine derivative
    
  • 3zkr - EchElic + anesthetic
    
  • 4a97, 4a98 – EchElic + benzodiazepine
    
  • 2yoe - EchElic + flurazepam + GABA
    
• Cyclic Nucleotide-Gated channel
  • 3etq, 3ffq, 3u0z, 3u10, 3u11 - mCNGC C-terminal
    
  • 1q3e, 1q43, 1q5o - mCNGC 2 fragment + nucleotide
    
  • 2q0a - mCNGC 2 C-terminal (mutant)
    
  • 3bpz - mCNGC 2 ligand-binding domain
    
  • 2zd9, 3beh - MlCNGC - Mesorhizobium loti
    
  • 4chv, 4chw – MlCNGC – Cryo EM
    
  • 2ptm - CNGC C-terminal - Strongylocentratus purpuratus
    
  • 3co2 - MlCNGC ligand-binding domain (mutant)
    
  • 3swf - CNGC CLZ domain - bovine
    
  • 2mpf – hCNGC 2 ligand-binding domain - NMR
    
  • 3swy – hCNGC 3 CLZ domain
    
  • 2kxl - ligand-binding domain – NMR
    
  • 3beh - MlCNGC
    
  • 3otf – hCNGC 4 ligand-binding domain
    
  • 2mng – hCNGC 4 ligand-binding domain - NMR
    
  • 4hbn – hCNGC 4 ligand-binding domain (mutant)
    
  • 4kl1 – hCNGC 4 C terminal + nucleotide
    
  • 4nvp – hCNGC 4 ligand-binding domain + 7-CH-cAMP
    
• Acid sensitive ion channel
  • 3hgc, 3ij4, 2qts, 3s3w, 4nyk, 3ij4 – cASC – chicken
    
  • 3s3x, 4fz0, 4fz1 – cASC + psalmotoxin
    
  • 4ntw, 4ntx, 4nty - cASC + neurotoxin + basic phospholipase A2
    
• ATP-Gated channel (AGC)
  • 3h9v, 3i5d – zeAGC
    
  • 4dw0 – zeAGC (mutant)
    
  • 4dw1 – zeAGC + ATP
    
• Proton channel
  • 2kih, 2kwx – IVproton channel – Influenza virus
    
  • 2rtf - IVproton channel + inhibitor - NMR
    
  • 3c9j - IVproton channel transmembrane domain + inhibitor
    
  • 3bkd - IVproton channel transmembrane domain
    
  • 1nyj, 1mp6 - IVproton channel transmembrane domain - NMR
    
  • 2kj1, 2l0j - IVproton channel – NMR
• Voltage-gated hydrogen channel (VGHC)

• • 3a2a – hVGHC C-terminal - NMR
    
  • 3wkv – mVGHC
    
  • 3vmx, 3vmy, 3vmz – mVGHC C-terminal
    
  • 3vn0, 3vyi – mVGHC C-terminal (mutant)
    
• Glycerol facilitator
  • 1lda, 1ldi - EcGlpF
    
  • 1fx8 - EcGlpF + glycerol
    
  • 1ldf - EcGlpF (mutant)

WeblinksWeblinks

• The TCDB database
• TCDB: 1.A α-Type channels
• TCDB: Transport proteins with PDB structures