DNA polymerase theta is an enzyme that in humans is encoded by the POLQgene.[5][6] This polymerase plays a key role in one of the three major double strand break repair pathways: theta-mediated end joining (TMEJ).[7][8][9][10] Most double-strand breaks are repaired by non-homologous end joining (NHEJ) or homology directed repair (HDR). However, in some contexts, NHEJ and HR are insufficient and TMEJ is the only solution to repair the break.[11] TMEJ is often described as alternative NHEJ, but differs in that it lacks a requirement for the Ku heterodimer, and it can only act on resected DNA ends.[12] Following annealing of short (i.e., a few nucleotides) regions on the DNA overhangs, DNA polymerase theta catalyzes template-dependent DNA synthesis across the broken ends, stabilizing the paired structure.[13][14]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Sharief FS, Vojta PJ, Ropp PA, Copeland WC (July 1999). "Cloning and chromosomal mapping of the human DNA polymerase theta (POLQ), the eighth human DNA polymerase". Genomics. 59 (1): 90–6. doi:10.1006/geno.1999.5843. PMID10395804.
^Schimmel J, van Schendel R, den Dunnen JT, Tijsterman M (September 2019). "Templated Insertions: A Smoking Gun for Polymerase Theta-Mediated End Joining". Trends in Genetics. 35 (9): 632–644. doi:10.1016/j.tig.2019.06.001. PMID31296341. S2CID195892718.