Abstract
Ligand-gated ionotropic glutamate receptors mediate a majority of excitatory synaptic transmission in the CNS and are involved in neuronal development, excitatoxicity, and synaptic plasticity. Previous studies have revealed that protein-protein interactions with the C-terminal domains of glutamate receptor subunits are involved in the modulation and clustering of receptor function at excitatory synapse. So far, mammalian studies have shown that the AMPA receptor subunit GluR2 has two C-terminal splicing isoforms. Tilapia ( Oreochomismossambicus ) expresses eight AMPA receptor subunits( tfGluR1-4α and tfGluR1-4β). C-terminal alternative splicing isoforms of tfGluR1α, tfGluR2α and tfGluR2β were found, whereas no C-terminal isoform of tfGluR1β was found. Wesurveyed that C-terminal splicing isoforms of AMPA recptor subunits ( zfGluR2α and zfGluR2β) of zebrafish ( Danio rerio ) and NMDA receptor subunits ( tfNR1αand tfNR1β) of tilapia. In this study, homologous screening, automated DNA sequencing and reverse-transcriptase PCR were employed to examine the molecular constitutions and C-terminal splicing isoforms of AMPA and NMDA receptor subunits of teleost. We found two C-terminal alternative splicing isoforms of zebrafish zfGluR2α, zfGluR2β and tilapia tfNR1β. Both zfGluR2α and zfGluR2β possess the PDZ-binding motif ( ESVKI ) in the short C-terminal form, and the short form of zfGluR2β also contains NSF-binding motif ( VAKNAQ ). All tfNR1β C-terminal alternative splicing isoforms contain PDZ-binding motif ( STVV ). Data from analysis of gene structure of the tfNR1β subunit suggests that tfNR1β lacks some nucleotides with a homology to the 5’end of exon 22 of rat rNR1 gene.