Biochemical Characterization and Localization of a Non‐N‐Methyl‐D‐Aspartate Glutamate Receptor in Rat Brain

Abstract: The structure and distribution of non‐N‐methyl‐D‐aspartate glutamate receptors in the rat brain were studied using subunit‐specific antibodies that recognize the receptor subunit GluRl. The GluRl protein, a 106‐kDa glycoprotein, appears predominantly in synaptic plasma membranes, where it is highly enriched in the postsynaptic densities. When synaptic plasma membranes are solubilized with the detergent 3‐[(3‐cholamidopropyl)dimethylammonio]‐l‐propanesul‐fonate, high‐affinity a‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) binding and GluRl immunoreactivity comigrate at a native Mr of 610,000. GluRl is enriched in the hippocampus and cerebellar cortex but is present throughout the CNS. It is found on neuronal cell bodies and processes within most regions of the brain; within the cerebellum, however, it is localized to the Bergmann glia. These data suggest that the GluRl protein is a subunit of multimeric AMPA‐preferring glutamate receptors present on neurons and on specialized glia.