Exon shuffling

An illustration of exon shuffling. In this example, two genes exchange exons (represented by colored boxes) through chromosomal crossover, resulting in the creation of two completely new genes.

Exon shuffling is a theory, introduced by Walter Gilbert in 1977, in which different exons either within a gene or between two nonallelic genes are occasionally mixed. Gilbert suggested that exons might each encode a single protein domain, establishing a kind of modular property. In this fashion, it would be possible for exons to essentially be "mixed and matched" to produce a variety of different proteins, yielded from different combinations of such exons and their resulting domain combinations.

The process of exon shuffling can create a mosaic, or chimeric, protein that is partly built of domains or segments which are similar or identical to domains of other proteins. The mosaic protein is created when an exon from one gene is integrated into another gene's intron. Another kind of exon shuffling is when an exon is duplicated in the same gene.

In the context of evolution, exon shuffling is significant due to its ability to quickly create new multidomain proteins, leading to increased variation in species.