Involved in the CpXpG methylation (e.g. CHG cytosine) and in gene silencing (PubMed:26798133). Methylates preferentially transposon-related sequences. Functionally redundant to DRM1/DRM2 to maintain non-CpG methylation. Involved in RNA-directed DNA methylation. a 2'-deoxycytidine in DNA + S-adenosyl-L-methionine = a 5-methyl-2'-deoxycytidine in DNA + H(+) + S-adenosyl-L-homocysteine Homodimer. Interacts with HP1 and, through its chromodomain, with the N-terminal tail of histone H3 doubly methylated at 'Lys-9' and 'Lys-27'. Binds to JMJ24 (PubMed:26798133). Ubiquitinated by JMJ24, subsequently beingargeted to proteasomal degradation thus initiating the destabilization of the heterochromatic state of endogenous silenced loci. Reduced DNA methylation (e.g. CHG cytosine) at least on FWA, QQS and SDC loci. Belongs to the class I-like SAM-binding methyltransferase superfamily. C5-methyltransferase family.