Neuron
Volume 8, Issue 1, January 1992, Pages 189-198
Journal home page for Neuron

Article
Divalent ion permeability of AMPA receptor channels is dominated by the edited form of a single subunit

https://doi.org/10.1016/0896-6273(92)90120-3Get rights and content

Abstract

Functionally diverse GIuR channels of the AMPA subtype are generated by the assembly of GIuR-A, -B, -C, and -D subunits into homo- and heteromeric channels. The GIuR-B subunit is dominant in determining functional properties of heteromeric AMPA receptors. This subunit exists in developmentally distinct edited and unedited forms, GIuR-B(R) and GIuR-B(Q), which differ in a single amino acid in transmembrane segment TM2 (Q/R site). Homomeric GIuR-B(R) channels expressed in 293 cells display a low divalent permeability, whereas homomeric GluR-B(Q) and GIuR-D channels exhibit a high divalent permeability. Mutational analysis revealed that both the positive charge and the size of the amino acid side chain located at the Q/R site control the divalent permeability of homomeric channels. Coexpression of Q/R site arginine- and glutamine-containing subunits generates cells with varying divalent permeabilities depending on the amounts of expression vectors used for cell transfection. Intermediate divalent permeabilities were traced to the presence of both divalent permeant homomeric and impermeant heteromeric channels. It is suggested that the positive charge contributed by the arginine of the edited GIuR-B(R) subunit determines low divalent permeability in heteromeric GIuR channels and that changes in GIuR-B(R) expression regulate the AMPA receptor-dependent divalent permeability of a cell.

References (27)

  • T.A. Gilbertson et al.

    Permeation of calcium ions through non-NMDA glutamate channels in retinal bipolar cells

    Science

    (1990)
  • O.P. Hamill et al.

    Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches

    Pflügers Arch.

    (1981)
  • A.L. Hodgkin et al.

    The effect of sodium ions on the electrical activity of the giant axon of the squid

    J. Physiol.

    (1949)
  • Cited by (0)

    View full text