Alternative Splicing of the Xmas mRNA Encoding the mRNA Export Protein in Drosophila melanogaster.

It is shown that Drosophila melanogaster has Xmas mRNA whose alternative splicing leads to the formation of three transcripts: Xmas, Xmas-2, and Xmas-1. As a result, three proteins are synthesized: Xmas, Xmas-2, and, presumably, Xmas-1. The size of the Xmas protein is close to the size of its homologue in humans. Adult flies contain large amounts of this protein, whereas in embryos it is absent.