Kainate receptors that are formed by subunits GRIK1 and or GRIK2 that are edited at the Q/R and other editing sites in GRIK2 are Ca2+ impermeable. They permit the passage of Na+ ions. Glutamine in GRIK1 at position 636 is replaced by arginine by an editing step which occurs posttranscriptioanlly. GRIK2 is glutamine 621 is edited to arginine. GRIK2 is also edited at 571 (Y/C) where a tyrosine residue is changed to cysteine and 567 (I/V) where an isoleucine is changed to valine. All three sites are edited postranscriptionally. A fully edited GRIK2 at all three sites is impermeable to calcium ions.