Figure 3

Cloning of four novel human AKT1 transcripts that are orthologous to the mouse Akt1m mRNA. (A) Schematic outline of the 5′ region of the human AKT1 gene with the two currently known untranslated exons (1, 2) and the location of a novel AKT1m exon according to sequence comparison between the mouse and human genome. Arrows indicate the forward primer within AKT1m and the reverse primer in the second coding exon (i.e., exon 4) that were used to clone novel mRNA variants that originate from an alternative genomic region. (B) PCR amplicons of cDNAs from human T47-D breast cancer cells that contain the novel AKT1m exon. The four strongest bands were cloned and the presence of the AKT1m exon was confirmed by sequencing. The sizes of the sequenced amplicons are shown in parentheses. (C) Graphic illustration of the four new human AKT1m transcript variants that originate from a previously unidentified exon. Note that all of these transcripts splice into the first coding exon, suggesting that all new transcripts encode the full-length AKT1 kinase.