Molecular determinants of single-channel conductance and ion selectivity in the Cys-loop family: insights from the 5-HT3 receptor

Trends Pharmacol Sci. 2005 Nov;26(11):587-94. doi: 10.1016/ Epub 2005 Sep 27.


The molecular determinants of the ionic selectivity and single-channel conductance of the Cys-loop family of transmitter-gated ion channels are beginning to be understood with increasing precision, in part, as a result of the recent availability of refined ultrastructural information for the archetype of the family, the nicotinic acetylcholine receptor (nAChR). Studies of another member of this family, the 5-HT(3) receptor, have now provided insight into the structure of its channel pore, the location of its gate and mechanisms of ion selectivity and translocation. The anomaly of the extremely low single-channel conductance of the homo-oligomeric 5-HT(3A) receptor has recently been solved, revealing that an intracellular domain of the protein is an important determinant of single-channel conductance. Such data are interpreted, in this article, in light of the most recent developments in structural characterization of the nAChR.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cysteine / chemistry
  • Humans
  • Ion Channel Gating
  • Ion Channels / chemistry
  • Ion Channels / genetics
  • Ion Channels / metabolism*
  • Ions
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Receptors, Nicotinic / chemistry
  • Receptors, Nicotinic / genetics
  • Receptors, Nicotinic / metabolism*
  • Receptors, Serotonin, 5-HT3 / chemistry
  • Receptors, Serotonin, 5-HT3 / genetics
  • Receptors, Serotonin, 5-HT3 / metabolism*


  • Ion Channels
  • Ions
  • Receptors, Nicotinic
  • Receptors, Serotonin, 5-HT3
  • Cysteine