Abstract
Glutamate plays an important role in the excitatorytransmission system in the mammalian brain. Glutamatereceptors may participate in basic functions of the brain suchas learning and memory. Two Oreochromis cDNA molecules, fGluR2α and fGluR2β, containing open reading frames that share 85%amino acid sequence identities to the rat glutamate receptorsubunit, Glur2. To characterize the gene structure of thefGluR2β gene, various restriction endonuclease-digestedfragments of the fGluR2β cDNA were used as probes to identifygenomic DNA fragments carrying exons of fGluR2β. The exon-intron junctions were determined by comparing cDNA and genomicDNA sequences. To obtain a full length fGluR2β cDNA, 5'-RACE(rapid amplification of cDNA ends) and 3'- RACE were employed.The incomplete fGluR2βgene spans more than 55 kb long andcontains at least 17 exons with splice junction donors andacceptors conforming to the consensus sequences. Theextraordinarily large size of the mouse intron 2 is conservedin the fGluR2β gene. 3'-alternative splicing is found in theC-terminal coding region of the fGluR2βgene transcripts. Thegene structures of the fGluR2β and mouse GluR2 are differentin that the fGluR2β gene contains at least one extra intronpresent in the region corresponding to the 5'-UTR of the fGluR2β.