CpG methylation is an epigenetic modification that is important for embryonic development, imprinting, and X-chromosome inactivation. DNMT3L is a nuclear protein with similarity to DNA methyltransferases, but is not thought to function as a DNA methyltransferase as it does not contain the amino acid residues necessary for methyltransferase activity. However, it does stimulate de novo methylation by DNA cytosine methyltransferase 3 alpha and is thought to be required for the establishment of maternal genomic imprints. It also mediates transcriptional repression through interaction with histone deacetylase 1. Recombinant human DNMT3L protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.