Figure 2.—

Mechanisms for mutagenesis in quasipalindromes involving replication template switching. (A) Sequence of an imperfect inverted repeat (boxed nucleotides will form base pairs in the quasipalindrome.) (B) Intramolecular template switching. Hairpin formation and templated mutation can occur by a template switch to copy one arm of the repeat, leading to perfection of the inverted repeat. A second template switch to resume normal replication produces the mutational event (shown in boldface type). Note that hairpin formation on leading and lagging strands leads to mutations on different sides of the inverted repeat.