Table 1

MMR, NER, and glycosylase genes and functions

MMR genes
E. coli HumanFunction
 Mut S hMSH2 Recognition of mismatched base
 hMSH3 Forms heterodimer with hMSH2
 hMSH6/GTBP/p160 Forms heterodimer with hMSH2
 Mut L hMLH1 Binds to MutS
 hPMS1 Forms heterodimer with hMLH1
 hPMS2 Forms heterodimer with hMLH1
 Mut H ? Strand scission
 Helicase II ? Unwinds the DNA
 Exonuclease I ? Degrading nicked strand
 DNA polymerase III ? Strand resynthesis
 single-stranded binding proteins ssb Binds to single-stranded DNA
 DNA ligase ? Restores DNA's phosphodiester backbone
NER genes
 XPA Associates with RPA and preferentially binds  to damaged DNA
 RPA Associates with XPA and acts as a single- stranded binding protein
 XPE-BF Stimulates UV damage-DNA binding
 XPC Preferentially binds to damaged or single-  stranded DNA and offers stabilization or protection of the pre-incision complex
 HHR23B Possibly stabilizes XPC
 TFIIH complex Helicase, involved in the formation of the   pre-incision complex, associated with transcription coupled repair
 XPG Cleavage of the DNA 3′ to the lesion
 ERCC1 Cleavage of the DNA 5′ to the lesion and  forms a tight complex with XPF
 XPF Cleavage of the DNA 5′ to the lesion and  forms a tight complex with ERCC1
 PCNA Associates with RFC to stimulate polymerase  binding
 RFC Associates with PCNA to stimulate  polymerase activity
 DNA polymerase δ/ɛ Incorporates complimentary nucleotide
 DNA ligase Restores phosphodiester backbone in DNA
Glycosylase genes
E. coli HumanFunction
 UDG (uracil-DNA glycosylase) UDG Repairs uracil in DNA
 TDG (thymine-DNA glycosylase) TDG Removes T from G:T mismatches
 AlkA (alkylation A) MPG Removes 3-meA
 Tag (three methyl adenine-DNA  glycosylase) ? Removes 3-meA
 Mut Y (mutator Y) MYH Removes A from 8-oxoG:A mismatches
 Endonuclease III1-a  Nth Removes thymine glycols
 Fpg (formamidopyrimidine-DNA  glycosylase)1-a  Ogg1, type 1a Removes 8-oxo G, and FaPy G/A Nuclear form
 Ogg1, type 2 Removes 8-oxo G, and FaPy G/A Mitochondrial form
 Ogg2 Removes 8-oxo G opposite A
  • 1-a  Class I AP endonucleases containing both glycosylase and lyase activity.