OGG1 splicing isoform beta contains a mitochondrial targeting sequence at the N terminus and lacks the C terminal nuclear localization signal. OGG1beta localizes to mitochondria (Nishioka et al. 1999), where it might participate in the repair of mitochondrial DNA, although its role in mitochondrial base excision repair has not been confirmed. OGG1beta G12E mutant, reported in kidney cancer, is unable to translocate to the mitochondrion as the missense mutation disrupts the mitochondrial targeting sequence (Audebert et al. 2002).