Nucleotide excision repair in eukaryotes. NER can be initiated by two slightly different methods in eukaryotes. One pathway (left) is similar to that occurring in bacteria, except that a larger section of lesion-containing DNA is removed. The other pathway (right) is referred to as transcription-coupled repair (TCR), because the lesion is first encountered by RNA polymerase, which then stalls. Some of the NER factors are bound to the RNA polymerase itself.