Native N-methyl-D-aspartate receptors containing NR2A and NR2B subunits have pharmacologically distinct competitive antagonist binding sites.
Christie JM, Jane DE, Monaghan DT. Native N-methyl-D-aspartate receptors containing NR2A and NR2B subunits have pharmacologically distinct competitive antagonist binding sites. J Pharmacol Exp Ther. 2000 Mar; 292(3):1169-74.