Figure 3.

(A) Sequences of the ssDNA products, AG34 and rev34, expected to be produced by pssXA plus pssXB(AG30) and by pssXA plus pssXB(rev), respectively, in comparison with AG30. Note that AG34 has 4 extra nt at the 3′ end relative to AG30 (indicated by the underlining). (B) Target substrate designed to investigate induction of intrachromosomal recombination by TFOs. LTK^– cells carrying, at a single chromosomal locus, two mutant copies of the TK gene as direct repeats flanking a polypurine third-strand binding site were used to test the ability of vector-generated ssDNAs to mediate triplex formation and recombination induction. The TK genes carry inactivating mutations consisting of XhoI linker insertions at the indicated positions. Potential recombinants are identified as TK+ clones growing in selective HAT-containing medium.