Ligand-gated ion channel



 

Neurotransmitter-gated ion-channel transmembrane region
Identifiers
Symbol Neur_chan_memb
Pfam PF02932
InterPro IPR006029
SCOP 1cek
TCDB 1.A.9
OPM family 14
OPM protein 2bg9
Available PDB structures:

1oedE:242-483 2bg9E:242-389 1dxzA:260-291 3mra :301-325 1a11 :276-298 1cekA:276-298 1eq8E:276-298 1motA:277-304 1vryA:281-337

Neurotransmitter-gated ion-channel ligand binding domain
Identifiers
Symbol Neur_chan_LBD
Pfam PF02931
InterPro IPR006202
SCOP 1lxg
Available PDB structures:

1ux2F:34-142 1uw6D:34-142 1i9bE:34-142 1uv6J:34-142 1yi5A:34-142 2bysD:23-226 2byrI:23-226 2byqA:23-226 2br7D:23-226 2bypC:23-225 2bynA:23-226 2bg9B:28-241 1lk1G:28-241 1olkE:28-241 1ol8B:26-230 1ol3A:26-230 1ol4B:26-230 1kl8B:201-219 1kc4B:201-219 1ol9A:26-230 1y5tB:230-235 1l4wB:206-226 1ljzB:206-226 1idgB:205-222 1tos :91-99 1lxgB:205-222 1lxhB:205-222 1idhB:205-222 1tor :91-100 1oleA:39-245 1olfA:29-235 1oljC:29-235


The Ligand-gated ion channels, also referred to as LGICs, or ionotropic receptors, are a group of intrinsic transmembrane ion channels that are opened or closed in response to binding of a chemical messenger, as opposed to voltage-gated ion channels or stretch-activated ion channels.[1]

Regulation

The postsynaptic electrical signal.

Many LGICs are additionally modulated by membrane potential.

Structure

Each subunit of the pentameric channels consist of the extracellular ligand-binding domain and a transmembrane domain. Each transmembrane domain in the pentamer includes four transmembrane helixes.[2]

Example: nicotinic acetylcholine receptor

The prototypic ligand-gated ion channel is the action potential is initiated.

Classification and examples

Many important ion channels are ligand-gated, and they show a great degree of homology at the genetic level. The Ligand-gated ion channels are classified into three superfamilies:

The Cys-loop receptors

  • anionic
    • GABAA
      • α1 (GABRA1), α2 (GABRA2), α3 (GABRA3), α4 (GABRA4), α5 (GABRA5), α6 (GABRA6)
      • β1 (GABRB1), β2 (GABRB2), β3 (GABRB3)
      • γ1 (GABRG1), γ2 (GABRG2), γ3 (GABRG3)
      • δ (GABRD), ε (GABRE), π (GABRP), θ (GABRQ)
    • GABAC
      • ρ1 (GABRR1), ρ2 (GABRR2), ρ3 (GABRR3)
    • Glycine (GlyR)
      • GlyR-α1 (GLRA1), GlyR-α2 (GLRA2), GlyR-α3 (GLRA3), GlyR-α4 (GLRA4)
      • GlyR-β (GLRB)
  • cationic
    • 5-HT3 serotonin receptor
      • 5-HT3A (HTR3A), 5-HT3B (HTR3B), 5-HT3C (HTR3C), 5-HT3D (HTR3D), 5-HT3E (HTR3E)
    • nicotinic acetylcholine receptor (nAChR)
      • nAChR-α1 (CHRNA1), nAChR-α2 (CHRNA2), nAChR-α3 (CHRNA3), nAChR-α4 (CHRNA4), nAChR-α5 (CHRNA5), nAChR-α6 (CHRNA6), nAChR-α7 (CHRNA7), nAChR-α8 (CHRNA8), nAChR-α9 (CHRNA9), nAChR-α10 (CHRNA10)
      • nAChR-β1 (CHRNB1), nAChR-β2 (CHRNB2), nAChR-β3 (CHRNB3), nAChR-β4 (CHRNB4)
      • nAChR-δ (CHRND), nAChR-ε (CHRNE), nAChR-γ (CHRNG)

The ionotropic glutamate receptors

  • AMPA
    • GluR1 (GRIA1), GluR2 (GRIA2), GluR3 (GRIA3), GluR4, alternatively called GluRA-D (GRIA4)
  • Kainate
    • GluR5 (GRIK1), GluR6 (GRIK2), GluR7 (GRIK3)
    • KA1 (GRIK4), KA2 (GRIK5)
  • NMDA
    • NR1 (GRIN1)
    • NR2A (GRIN2A), NR2B (GRIN2B), NR2C (GRIN2C), NR2D (GRIN2D)

The ATP-gated channels

  • P2X
    • P2X1 (P2RX1), P2X2 (P2RX2), P2X3 (P2RX3), P2X4 (P2RX4), P2X5 (P2RX5), P2X7 (P2RX7), P2XL1 (P2RXL1)

Clinical relevance

Ligand-gated ion channels are likely to be the major site at which anaesthetic agents have their effects, although unequivocal evidence of this is yet to be established.[3][4] In particular, the NMDA receptors are affected by anaesthetic agents at concentrations similar to those used in clinical anaesthesia.[5]

See also

References

  1. ^ Connolly CN, Wafford KA (2004). "The Cys-loop superfamily of ligand-gated ion channels: the impact of receptor structure on function". Biochem. Soc. Trans. 32 (Pt3): 529–34. doi:10.1042/BST0320529. PMID 15157178.
  2. ^ Cascio M (2004). "Structure and function of the glycine receptor and related nicotinicoid receptors". J. Biol. Chem. 279 (19): 19383–6. doi:10.1074/jbc.R300035200. PMID 15023997.
  3. ^ Krasowski MD, Harrison NL (1999). "General anaesthetic actions on ligand-gated ion channels". Cell. Mol. Life Sci. 55 (10): 1278–303. doi:10.1007/s000180050371. PMID 10487207.
  4. ^ Dilger JP (2002). "The effects of general anaesthetics on ligand-gated ion channels". Br J Anaesth 89 (1): 41–51. doi:10.1093/bja/aef161. PMID 12173240.
  5. ^ Harris RA, Mihic SJ, Dildy-Mayfield JE, Machu TK (1995). "Actions of anesthetics on ligand-gated ion channels: role of receptor subunit composition". FASEB J. 9 (14): 1454–62. PMID 7589987.
v • d • e
Voltage-gated ion channel • Ligand-gated ion channel • Cyclic nucleotide-gated ion channel (α1, α3, β3, H1, H2, H4) • Stretch-activated ion channel
v • d • e
P2X (1, 4, 5, 7))
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ligand-gated_ion_channel". A list of authors is available in Wikipedia.