Histone methyltransferase family member that plays a central role in gene silencing (PubMed:15775980, PubMed:16384625, PubMed:19043555, PubMed:24463519, PubMed:27171427). Together with MORC6 and SUVH9, regulates the silencing of some transposable elements (TEs) (PubMed:27171427). According to PubMed:15775980, it is required for normal methylation of 'Lys-9' and 'Lys-27' of histone H3, 'Lys-20' of H4, and cytosine, but PubMed:19043555 see no significant effect on histone methylation when the gene is mutated. According to PubMed:19043555, the protein does not bind S-adenosyl-L-methionine and lacks methyltransferase activity. Instead, it may function downstream of DRM2 in RNA-directed DNA methylation, binding to methylated DNA and recruiting DNA-directed RNA polymerase V to chromatin (PubMed:24463519, PubMed:27171427). Self-interacts (PubMed:24465213). Interacts with DNA-directed RNA polymerase V subunit NRPE1 and with DRD1 and DMS3 (PubMed:24463519, PubMed:24465213). Binds to MORC1/CRT1 (PubMed:24465213). Associates with centromeric constitutive heterochromatin. Expressed at low levels in leaves stems and flowers. Although both SET and pre-SET domains are present, the absence of the post-SET domain may explain the lack of methyltransferase activity. Besides, the Cys residues in the SET domain that normally bind a zinc ion are not conserved. In the pre-SET domain, Cys residues bind 3 zinc ions that are arranged in a triangular cluster; some of these Cys residues contribute to the binding of two zinc ions within the cluster. Impaired gene silencing due to decondensation of chromocenters leading to the derepression of DNA-methylated genes and transposable elements (TEs). Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. Suvar3-9 subfamily.