A mRNA molecule encoding truncated excitatory amino acid carrier 1 (EAAC1) protein (EAAC2) is transcribed from an independent promoter but not an alternative splicing event

A mRNA molecule encoding truncated excitatory amino acid carrier l(EAAC1)protein(EAAC2)is transcribed from an independent promoter but not analternative splicing event

Glutamate transporter EAACl removes excitatory neurotransmitter in central nervous system, and also absorbs glutamate in epithelia of intestine, kidney, liver and heart for normal cell growth. When a mouse cDNA was screened using EAACl cDNA fragment as probe in our lab, a transcript (GenBank U75214) encoding an EAACl protein with 148 residues truncated at N-terminal was cloned and named as EAAC2. Sequence analysis shows that EAAC2 has it's own start code and unique 5'UTR that is different from that of EAACl. A mouse genomic library was screened and a positive clone including EAACl CDS was sequenced (GenBank AF 322393) and indicates that normal EAACl transcript (GenBank U73521) is transcribed from 10 exons in terms of exon Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, Ⅵ, Ⅶ, Ⅷ,Ⅸ, Ⅹ, and EAAC2 transcript is consisted by exons from IV to IX as same as that of EAACl and with its unique exon β upstream to exon Ⅳ and exon δ downstream to IX. EAAC2 transcript has a cluster of transcriptional start sites not overlapping with the transcriptional start sites of EAACl. These results indicate that EAAC2 is transcribed from an independent promoter but not an alternative splicing event.