Mobile introns and intron-encoded proteins.

genomes of eukaryotes arose by a process of exon shuffling (1). Once formed, the intervening sequences would be free to evolve in the absence of direct selection pressures to forms no longer recognizable (or barely so) from their progenitors. In this perspective, we review and discuss some implications of recent findings of directed insertion of a class of related intron elements. These new data raise the likelihood that intron mobility was another source of split genes.

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