The Restriction endonuclease AspBHI N-terminal (PF18062) is a homotetrameric protein that recognizes 5-methylcytosine in the context of a double-stranded DNA sequence of (C/T) (C/G) (5mC) nucleotides. It cleaves both strands to the modified cytosine at a fixed distance (N12/N16). 3. The N-terminal domain is structurally and functionally analogous to the SRA's 5-methylcytosine binding domain, and it is responsible for DNA recognition.