CONTROL OF KINETIC-PROPERTIES OF AMPA RECEPTOR CHANNELS BY NUCLEAR-RNA EDITING

AMPA lpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor channels mediate the fast component of excitatory postsynaptic curren ts in the central nervous system. Site-selective nuclear RNA editing c ontrols the calcium permeability of these channels, and RNA editing at a second site is shown here to affect the kinetic aspects of these ch annels in rat brain. In three of the four AMPA receptor subunits (GluR -B, -C, and -D), intronic elements determine a codon switch (AGA, argi nine, to GGA, glycine) in the primary transcripts in a position termed the R/G site, which immediately precedes the alternatively spliced mo dules ''flip'' and ''flop.'' The extent of editing at this site progre sses with brain development in a manner specific for subunit and splic e form, and edited channels possess faster recovery rates from desensi tization.