DNMT3A (UniProtKB/Swiss-Prot entry Q9Y6K1) catalyses the genome wide de novo methylation of CpG residues. DNA methylation on CpG residues by DNMT3A regulates gene expression and is essential for development. DNMT3A is strongly expressed in embryonic stem cells, but low in adult somatic cells. DNA methylation is coordinated with methylation of histones. DNMT3A binds to SETDB1 and HDAC1, and is involved in the repression of transcription from promoters containing an E2F binding site.