Figure 2.

Two alternative transcription start sites of MYO15A, three isoform classes and data supporting a novel exon 1 of isoform 3 identified in both human and mouse. A: Transcription for isoforms 1 and 2 starts from exon 1, whereas isoform 3 uses an alternate transcription start site of a second exon 1 located in intron 2. We identified this novel exon 1 of isoform 3 through 5′RACE from mouse pituitary cDNA and later confirmed it by PCR amplification and Sanger sequencing. Location of primers used to amplify and sequence novel exon 1 from mouse and human pituitary tissue cDNA are shown by arrows above and below exons, respectively. Lines indicate splicing of the primary transcript. Coloring of exons is the same as in Fig. 1A, except for the novel exon 1 (purple) of isoform 3 not illustrated in Fig 1. B: Images of 2% agarose gels used to size-separate amplicons. Each primer pair used to amplify cDNA was also used to amplify genomic DNA as a control template. Bands in lanes 4, 8 (upper band) and 13 show that the commercial cDNA libraries also contained some genomic DNA. C: Clustal Omega alignments of the 50 amino acid residues encoded by exon 1 of isoform 3. Non-identical amino acids are highlighted in red font whereas identical amino acids for all species examined are noted with a star. gDNA, genomic DNA; cDNA, complementary DNA; nt, nucleotide.