Identification and structural characterization of two genes encoding glutamate transporter homologues differently expressed in the nervous system ofDrosophila melanogaster

In vertebrates, excitatory amino acid transporters (EAATs) are believed to mediate the removal of glutamate released at excitatory synapses and to maintain extracellular concentrations of this neurotransmitter below excitotoxic levels. Glutamate is also used in insects as an excitatory neurotransmitter at the neuromuscular junction and probably in the central nervous system where its role remains to be established. We report the molecular characterization and developmental expression pattern of two Drosophila cDNAs: dEAAT1, which has recently been identified as a high affinity glutamate transporter [1], and dEAAT2, a novel protein sharing strong homology to dEAAT1 and to the mammalian EAAT protein family. The developmental expression pattern of the two Drosophila EAAT genes has been compared by Northern blot analysis and whole-mount in situ hybridizations. The two transporters are transcribed in distinct cell types of the nervous system and are strongly expressed in the adult visual system.