Molecular structure and pharmacological characterization of humEAA2, a novel human kainate receptor subunit

A cDNA encoding a novel human glutamate receptor subunit protein was isolated from a human hippocampal library. This cDNA, termed humEAA2, is most closely related to rat cDNAs for kainate receptor proteins and, when expressed in COS cells, is associated with high affinity kainate receptor binding. The relative potency of compounds in displacing [3H]kainate binding was kainate greater than quisqualate greater than domoate greater than L-glutamate much greater than 6,7-dinitroquinoxaline-2,3-dione greater than dihydrokainate greater than 6-cyano-7-nitroquinoxaline-2,3-dione greater than (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid. Homomeric expression of humEAA2 does not appear to elicit ligand-gated channel activity. Nevertheless, the molecular structure and pharmacology of high affinity kainate binding suggest that humEAA2 is a novel subunit protein of a human kainate receptor complex.