NCIt definition : Nucleotide Excision Repair (NER) mends DNA regions that contain chemical adducts,
such as UV-induced thymine dimers or carcinogenic adducts, which distort the DNA helix
and interfere with replication and transcription. NER is targeted to actively transcribed
regions of the genome. During NER in eukaryotes, shape irregularities are detected
by protein complexes that slide along the DNA molecule and induce cuts on each side
of a lesion several nucleotides away. Removal of the damaged 25-30 nucleotide fragment
is followed by repair synthesis and ligation.;