GRIK2 is edited at the Q/R site at 621 where the glutamine 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 totally impermeable to calcium ions.