Glutamate receptors are the predominant excitatory neurotransmitter receptors in the mammalian brain and are classified on the basis of their activation by different agonists. The agonists kainate and alpha-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid define a class of glutamate receptors termed kainate receptors. We have isolated and sequenced a human glutamate receptor (GluHI) cDNA and determined the chromosomal localization of its gene. The DNA sequence of GluHI would encode a 907-amino acid protein that has a 97% identity to one of the rodent kainate receptor subunits. Many of the changes between the predicted amino acid sequence of GluHI and the most similar rodent kainate receptor (GluRI) occur in a region of the protein encoded in rodents by an alternatively spliced exon. The extreme conservation between the human and rat kainate receptor subunits suggests that a similar gene family will encode human kainate receptors. The GluHI mRNA is widely expressed in human brain. The human gene encoding the GluHI subunit is located at 5q33. While the GluHI gene is not located near a chromosomal region associated with any human neurogenetic disorders, the homologous region on mouse chromosome 11 contains the sites of five neurologic mutations.