Identification of the diverse transcripts of human <i>FXN.</i>

<p>(<b>A</b>) Schematic diagram of transcripts of human <i>FXN</i>. One arrow shows the position of the primer for reverse transcription, locating in exon 4 used for 5′-RACE with RNA from HEK293 cells. PCR products were sequenced to identify the transcripts. Exon1A is the first canonical exon (only the size of coding region shown); exon1A△141, exon1A missing the last 141 nucleotides; exon1B, the novel exon 1 locating in the first intron; exon1B△18, missing 18 nucleotides near the 5′-end of exon1B; △exon3, transcript missing exon3. (<b>B</b>) Transcripts of human <i>FXN</i> dectected with RT-PCR showed tissue-specific expression pattern. C: cerebellum; H: heart; M: skeletal muscle. (<b>C</b>) Diverse transcripts may exist in cells, unveiled by Northern blot. (<b>D</b>) Potential <i>FXN</i> transcripts from AceView database, verified when human tissues or cell lines were used. Here are only shown transcripts a, b, d, e, and f. See <a href="http://www.ncbi.nlm.nih.gov/IEB/Research/Acembly/av.cgi?c=geneid&org=9606&l=2395" target="_blank">http://www.ncbi.nlm.nih.gov/IEB/Research/Acembly/av.cgi?c=geneid&org=9606&l=2395</a>. Flagged ones (a,b,d) are annotated to be validated. The correlation between the mRNA identified in this study and those annotated in AceView database is linked by spotted lines. Transcript a and b are not distinguishable and are considered as canonical ones because the primer used for 5′-RACE positions within exon 4 of human <i>FXN</i>. Scale: 200 bp.