Binds CpG islands in promoters where the DNA is methylated at position 5 of cytosine within CpG dinucleotides. Binds hemimethylated DNA as well. Recruits histone deacetylases and DNA methyltransferases. Acts as transcriptional repressor and plays a role in gene silencing. Functions as a scaffold protein; targeting GATAD2A and GATAD2B to chromatin to promote repression. May enhance the activation of some unmethylated cAMP-responsive promoters. {ECO:0000269|PubMed:10471499; ECO:0000269|PubMed:10947852; ECO:0000269|PubMed:12665568; ECO:0000269|PubMed:16415179; ECO:0000269|PubMed:24307175; ECO:0000269|PubMed:9774669}.