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. Author manuscript; available in PMC: 2008 Mar 1.
Published in final edited form as: Mutat Res. 2006 Dec 8;616(1-2):46–59. doi: 10.1016/j.mrfmmm.2006.11.021

Figure 3. Three Variations of Synthesis-Dependent Strand Annealing (SDSA).

Figure 3

a) invasion of the undamaged template chromosome simultaneously by both 3' strands (indicated by yellow arrows) of the broken chromosome primes the synthesis of new DNA. Unlike the DBSR model, however, the newly synthesized strands anneal together and result in no crossover. b) In this model, only one strand invades the target template. Following synthesis, the new DNA strand reattaches to the originally damaged chromosome at a homologous location, resulting in a gene conversion repair without crossover. c) In this scenario, the DSB occurs adjacent to a TE insertion. The 3' end of the broken DNA strand invades the template strand at a nonallelic yet homologous TE locus. Synthesis occurs, copying both the homologous TE locus as well as the nonhomologous sequence flanking it. NHEJ is then used to reunite the newly synthesized sequence to the original damaged chromosome.