Table 1.

End processing factors

Factor*	Activity
APTX	Removes 5′-adenylate adducts [40]
PNKP	Removes 3′ phosphates and phosphorylates 5′ hydroxyls [45]
APLF	Histone chaperone [59] 3′-5′ exonuclease, endonuclease [56,61]
TDP1	Removes Top I adducts [63], 3′ deoxyribose fragments [47,67,68]
TDP2	Removes Top II adducts [64]
XRCC5,XRCC6 (Ku)	Removes 5′-dRP residues and abasic sites [27]
POLM (Pol λ)	Fills in gaps when ends align with no complementarity [90]
POLL (Pol μ)	Fills in gaps when ends are partly complementary [86,90]
DCLRE1C (Artemis)	Endonuclease, 5′-3′ exonuclease [100]
WRN	3′-5′ exonuclease [121,122] and 3′-5′ helicase [120]
MRE11/RAD50/NBN (MRN)	3′-5′ exonuclease, endonuclease [101,129]
SETMAR (Metnase)	Endonuclease/exonuclease [103]

*HUGO gene nomenclature: APTX, aprataxin; PNKP, polynucleotide kinase 3^′-phosphatase; APLF, aprataxin and PNKP like factor; TDP1, tyrosyl-DNA phosphodiesterase 1; TDP2, tyrosyl-DNA phosphodiesterase 2; XRCC5,XRCC6 (Ku80, Ku70), X-ray repair complementing defective repair in Chinese hamster cells 5/6; POLM, polymerase mu; POLL, polymerase lambda; DCLRE1C (Artemis), DNA cross-link repair 1C; WRN, Werner syndrome; MRE11/RAD50/NBN, meiotic recombination 11 homolog/RAD50 homolog/nibrin (Nbs1), SETMAR, SET domain and mariner transposase fusion gene (Metnase).