Fig. 6.

Diagram of the TMEJ process. Pol θ helps to anneal two broken DNA ends with 3′ overhangs by searching for microhomology of 3–4 bp. If microhomology is located internally in either overhang, a 3′–5′ exonuclease or flap endonuclease will be needed to trim off the overhangs for efficient extension by Pol θ. After removal of 3′ overhangs, Pol θ extends the microduplex by template-dependent DNA synthesis using both ends as primers either alternately (if the microduplex is short) or simultaneously (if the duplex is long enough to accommodate a Pol θ dimer).