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. Author manuscript; available in PMC: 2021 Oct 26.
Published in final edited form as: Essays Biochem. 2020 Oct 26;64(5):687–703. doi: 10.1042/EBC20200009

Figure 2. An overview of DNA methylases and demethylases.

Figure 2.

(A) Structural depiction of cytosine methylation to form 5mC. Upon TET activity, 5mC can give rise to 5-hydroxymethylcytosine (5hmC). TETs can iteratively oxidize 5hmC to 5-formylcytosine (5fC) and 5-carboxycytosine (5caC). 5fC and 5caC can be recognized and excised by the action of TDG forming cytosine through BER. (B) DNA methylation in adenine. Adenine can be methylated by N6AMT1 in DNA. The m6A RNA methyltransferase MettL3–MettL14 has been suggested to also methylate ssDNA. Demethylation has been suggested to occur via ALKBH1 activity. DNMT - includes DNMT1, DNMT3A, DNMT3B; TETs - TET1, TET2, TET3. Abbreviations: BER, base excision repair; N6AMT1, N6-adenine-specific DNA methyltransferase 1; TDG, thymine DNA glycosylase.