ALTERNATIVE SPLICING OF 5'-TERMINAL EXONS IN HUMAN TRYPTOPHANYL-TRANSFER-RNA SYNTHETASE GENE

Three isoforms of the hWRS mRNA were studied in seven human cell cultu res: CaOv, GEM, CK-27, J-41, J-96, H9, and MT-4. Earlier we have shown that all three isoforms contain nucleotide sequences of IA and IB 5'- terminal exons. Here we demonstrate equal participation of these isofo rms in the response to IFN alpha or IFNg. All three forms were found i n each of the seven cell cultures, their relative content in WRS mRNA was stable. Two isoforms are generated from the same primary transcrip t by alternative splicing. The exon IA may bind either by its 5' end t o exon IB, or directly to exon II. The third isoform lacking exon IB a nd the upstream part of exon IA is formed from the additional transcri ption initiation site located downstream from the first one. Alternati ve splicing is not affected by IFN and has no specific preference for any of the cell lines studied.