Mouse methyltransferase for repair of O6-methylguanine and O4-methylthymine in DNA

Hisaya Kawate, Kenji Ihara, Kohfuku Kohda, Kunihiko Sakumi, Mutsuo Sekiguchi

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


cDNA for mouse O6-methylguanine-DNA methyltransfer-ase was expressed in methyltransferase-deficient Escher-ichia coli mutant cells, and the overproduced mouse enzyme was purified to a homogeneous state. Using this purified product, polyclonal antibodies were prepared and used to estimate amounts of the methyltransferase protein in cells. A single cell of NIH3T3 contained 1.8 ×104molecules of the methyltransferase protein. When mouse fibroblasts were immunostained, it was shown that most of the methyltransferase protein exists in the cytoplasm rather than in the nucleus. Using double-stranded oligomers containing a single O6-methylguanine or O4-methylthymine at predetermined sites, the mouse enzyme repaired O6-methylguanine and O4-methylthymine, at an almost equal efficiency. In the LacZ reversion assay, MNNG-induced A: T to G: C as well as G: C to A: T transition mutations were efficiently suppressed by the function of mouse methyltransferase, in vivo.

Original languageEnglish
Pages (from-to)1595-1602
Number of pages8
Issue number7
Publication statusPublished - Jul 1995

All Science Journal Classification (ASJC) codes

  • Cancer Research


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