DNA methylation can contribute to transcriptional silencing through several transcriptionally repressive complexes, which include methyl-CpG binding domain proteins (MBDs) and histone deacetylases (HDACs). The chief enzyme that maintains mammalian DNA methylation, DNMT1, can also establish a repressive transcription complex. The non-catalytic amino terminus of DNMT1 binds to HDAC2 and DMAP1 (for DNMT1 associated protein), and can mediate transcriptional repression. DMAP1 has intrinsic transcription repressive activity, and binds to the transcriptional co-repressor TSG101. DMAP1 is targeted to replication foci through interaction with the far N terminus of DNMT1 throughout S phase, whereas HDAC2 joins DNMT1 and DMAP1 only during late S phase, providing a platform for how histones may become deacetylated in heterochromatin following replication [1].

1: DNMT1 binds HDAC2 and a new co-repressor, DMAP1, to form a complex at replication foci. Rountree MR, Bachman KE, Baylin SB; Nat Genet 2000;25:269-277. PMID:10888872