A mechanism for interchanging genes, e.g. the a and α genes that determine mating type in yeast. A double-stranded nuclease makes a cut at a specific point in the MAT (mating type) locus and the old gene is replaced with a copy of a silent gene (a different cassette) from one or other flanking regions, and the new copy becomes active. Similar mechanisms are used in some cloning vectors.
Subjects: Medicine and Health.