Fig. 1.

Characterization of C2C12 myotube skeletal muscle fast troponin T (Tnnt3) splice forms. A: mouse Tnnt3 pre-mRNA contains 18 exons. While the 5′-end alternative exon cassette (i.e., exons 4–9), combined with mutually exclusive 3′-end exons 16 and 17, can give rise to potentially 128 different splice forms, only 15 Tnnt3 splice forms (labeled mt1-mt15) were detected. Tnnt3 splice forms for which exon composition is represented by gray X's have not yet been verified by cloning and sequencing. The relative abundance of each Tnnt3 splice form at day 7 of differentiation is indicated on the right [values are means (SE)]. B: fluorescently labeled Tnnt3 PCR amplicons from C2C12 myotubes separated by means of capillary electrophoresis (gray trace). Intensity (height) of peaks is proportional to the mRNA splice form abundance in the original RNA sample. Internal size standards are represented by the black trace. UTR, untranslated region.