OGG1 is the primary enzyme responsible for the excision of 8-oxoguanine (8-oxoG), a mutagenic base byproduct that occurs as a result of exposure to reactive oxygen species (ROS). OGG1 is a bifunctional glycosylase, as it is able to both cleave the glycosidic bond of the mutagenic lesion and cause a strand break in the DNA backbone. Alternative splicing of the C-terminal region of this gene classifies splice variants into two major groups, type 1 and type 2, depending on the last exon of the sequence. Type 1 alternative splice variants end with exon 7 and type 2 end with exon 8. All variants have the N-terminal region in common. Many alternative splice variants for this gene have been described, but the full-length nature for every variant has not been determined. In eukaryotes, the N-terminus of this gene contains a mitochondrial targeting signal, essential for mitochondrial localization. A conserved N-terminal domain contributes residues to the 8-oxoguanine binding pocket. This domain is organised into a single copy of a TBP-like fold.
Despite the presumed importance of this enzyme, mice lacking Ogg1 have been generated and found to have a normal lifespan, and Ogg1 knockout mice have a more possibility to develop cancer ,whereas Mth1 gene disruption concomitantly suppresses lung cancer development in Ogg1-/- mice.[dubious– discuss] Interestingly, mice lacking Ogg1 have been shown to be prone to increased body weight and obesity, as well as high-fat diet induced insulin resistance. There is some controversy as to whether deletion of Ogg1 actually leads to increased 8-oxo-dG levels: the HPLC-EC assay suggests up to 6 fold higher levels of 8-oxo-dG in nuclear DNA and 20-fold higher in mitochondrial DNA whereas the fappy-glycosylase assay indicates no change.
^Bjoras M, Seeberg E, Luna L, Pearl LH, Barrett TE (March 2002). "Reciprocal "flipping" underlies substrate recognition and catalytic activation by the human 8-oxo-guanine DNA glycosylase". J. Mol. Biol.317 (2): 171–7. doi:10.1006/jmbi.2002.5400. PMID11902834.
^Marsin S, Vidal AE, Sossou M, Ménissier-de Murcia J, Le Page F, Boiteux S, de Murcia G, Radicella JP (November 2003). "Role of XRCC1 in the coordination and stimulation of oxidative DNA damage repair initiated by the DNA glycosylase hOGG1". J. Biol. Chem.278 (45): 44068–74. doi:10.1074/jbc.M306160200. PMID12933815.
Boiteux S, Radicella JP (2000). "The human OGG1 gene: structure, functions, and its implication in the process of carcinogenesis.". Arch. Biochem. Biophys.377 (1): 1–8. doi:10.1006/abbi.2000.1773. PMID10775435.
Park J, Chen L, Tockman MS et al. (2004). "The human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) DNA repair enzyme and its association with lung cancer risk". Pharmacogenetics14 (2): 103–9. doi:10.1097/00008571-200402000-00004. PMID15077011.
Hung RJ, Hall J, Brennan P, Boffetta P (2006). "Genetic polymorphisms in the base excision repair pathway and cancer risk: a HuGE review". Am. J. Epidemiol.162 (10): 925–42. doi:10.1093/aje/kwi318. PMID16221808.
Mirbahai L, Kershaw RM, Green RM, Hayden RE, Meldrum RA, Hodges NJ. (2010). "Use of a molecular beacon to track the activity of base excision repair protein OGG1 in live cells". DNA Repair9 (2): 144–152. doi:10.1016/j.dnarep.2009.11.009. PMID20042377.