DNA CpG methylation and histone H3 lysine 9 (H3K9) methylation are two major 
repressive epigenetic modifications, and these methylations are positively 
correlated with one another in chromatin. Here we show that G9a or G9a-like 
protein (GLP) dimethylate the amino-terminal lysine 44 (K44) of mouse Dnmt3a 
(equivalent to K47 of human DNMT3A) in vitro and in cells overexpressing G9a or 
GLP. The chromodomain of MPP8 recognizes the dimethylated Dnmt3aK44me2. MPP8 
also interacts with self-methylated GLP in a methylation-dependent manner. The 
MPP8 chromodomain forms a dimer in solution and in crystals, suggesting that a 
dimeric MPP8 molecule could bridge the methylated Dnmt3a and GLP, resulting in a 
silencing complex of Dnmt3a-MPP8-GLP/G9a on chromatin templates. Together, these 
findings provide a molecular explanation, at least in part, for the 
co-occurrence of DNA methylation and H3K9 methylation in chromatin.