A highly conservative, cyclically permuted, non-homologous exchange among three unrelated DNA sequences in bleomycin-treated CHO cells.

Molecular analysis of a bleomycin-induced rearrangement of the aprt gene in CHO cells revealed that it consisted of a nearly perfect three-way exchange among non-homologous sequences, consistent with a mechanism involving cyclically permuted misjoining of the six ends of three double-strand breaks.