Single-channel properties of recombinant AMPA receptors depend on RNA editing, splice variation, and subunit composition

J Neurosci. 1997 Jan 1;17(1):58-69. doi: 10.1523/JNEUROSCI.17-01-00058.1997.

Abstract

Non-NMDA glutamate receptor subunits of the AMPA-preferring subfamily combine to form ion channels with heterogeneous functional properties. We have investigated the effects of RNA editing at the Q/R site, splice variation of the "flip/flop" cassette, and multimeric subunit assembly on the single-channel conductance and kinetic properties of the recombinant AMPA receptors formed from GluR2 and GluR4 expressed in HEK 293 cells. We found that AMPA receptor single-channel conductance was dependent on the Q/R site editing state of the subunits comprising the channel. Calcium-permeable (unedited) channels had resolvable single-channel events with main conductance states of 7-8 pS, whereas fully edited GluR2 channels had very low conductances of approximately 300 fS (estimated from noise analysis). Additionally, the flip splice variant of GluR4 conferred agonist-dependent conductance properties reminiscent of those found for a subset of AMPA receptors in cultured cerebellar granule cells. These results provide a description of the single-channel properties of certain recombinant AMPA receptors and suggest that the single-channel conductance may be determined by the expression of edited GluR2 subunits in neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Electric Conductivity
  • Ion Channels / chemistry
  • Ion Channels / genetics*
  • Ion Channels / physiology*
  • Kinetics
  • RNA Editing*
  • RNA Splicing*
  • Receptors, AMPA / chemistry
  • Receptors, AMPA / genetics*
  • Receptors, AMPA / physiology*
  • Recombinant Proteins

Substances

  • Ion Channels
  • Receptors, AMPA
  • Recombinant Proteins