Molecular cloning and expression of the rat EAAT4 glutamate transporter subtype

Glutamate transport is a primary mechanism for the synaptic inactivation of glutamate. Excitatory amino acid transporter 4 (EAAT4) is a novel glutamat e transporter with properties of a ligand-gated chloride channel that was r ecently cloned from human brain. Here we report the cloning of rat EAAT4 (r EAAT4) cDNA from rat cerebellum. The nucleotide sequence of rEAAT4 was 88% identical to the human sequence, and the predicted peptide was 89% identica l to the human protein. The transport activity encoded by rEAAT4 has high a ffinity for L-glutamate. In Xenopus laevis oocytes expressing rEAAT4, L-glu tamate and other transporter substrates elicited a current predominantly ca rried by chloride ions. Like human EAAT4, the rEAAT4 mRNA was largely restr icted to cerebellar Purkinje cells; the rEAAT4 protein was localized to Pur kinje cell somas and dendrites. (C) 1998 Elsevier Science B.V. All rights r eserved.