Overview:

DNMT3L is an enzymatically inactive regulatory factor that shares sequence homology with the DNA methylatransferase DNMT3A and DNMT3B. DNMT3L is involved in the establishment of DNA methylation patterns during gametogenesis. In mammals, DNA methylation is used for heritable silencing of retrotransposons and imprinted genes and for inactivation of the X chromosome in females (1). DNMT3L has a genomewide role in CpG island methylation beyond genomic imprinting (2). DNMT3L functions as a regulators of methylation at imprinted loci rather than a DNA cytosine methyltransferase because of a lack of catalytic motifs in its sequence.

References:

1. Ooi, S.K.T. et al: DNMT3L connects unmethylated lysine 4 of histone H3 to de novo methylation of DNA. Nature 448: 714-717, 2007.2. Smallwood, S. A. et al: Dynamic CpG island methylation landscape in oocytes and preimplantation embryos. Nature Genet. 43: 811-814, 2011.