Acts as transcriptional repressor and plays a role in gene silencing. Does not bind to DNA by itself (PubMed:12124384). Binds to DNA with a preference for sites containing methylated CpG dinucleotides (in vitro). Binds to a lesser degree DNA containing unmethylated CpG dinucleotides (PubMed:24307175). Recruits histone deacetylases and DNA methyltransferases.