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Figure 1 | Genome Biology

Figure 1

From: Technology transfer from worms and flies to vertebrates: transposition-based genome manipulations and their future perspectives

Figure 1

'Cut and paste' DNA transposition. (a) Scheme of a class II 'cut and paste' transposable element (TE) and that of a binary transposition system created by dissecting the transposase source from the transposon. (b) Outline of the mechanism of 'cut and paste' transposition and the DNA repair events that complete the transposition reaction. The model shows transposition of a Tc1/mariner element. The transposase introduces double strand DNA breaks at the ends of the transposon. Tc1/mariner elements generate 3' overhangs of varying length at the excision sites. At the excision site, nonhomologous end joining (NHEJ) typically generates a footprint (FP) that consists of the terminal base pairs of the transposon. Homology dependent DNA repair (HDR) can also contribute to repairing the transposase induced gaps. HDR can restore the wild-type sequence in cells that are heterozygous for the transposon insertion, if the homologous chromosome is available as a template. HDR can also restore either complete or partial transposon sequences at the excision site, if a homologous template containing a copy of the transposon is available. HDR may also generate deletions of flanking sequences at the excision site. The excised transposon integrates into a new TA target sequence. The single stranded gaps flanking the integrated element are repaired and give rise to target site duplications (TSD) flanking the newly integrated element. ITR, inverted terminal repeat.

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