Regulator of RNA-directed DNA methylation (RdDM). Binds to single-stranded methyl DNA. Involved in the assembly of RNA polymerase V (Pol V) transcription initiation or elongation complexes at the chromatin, as a component of the DDR complex. Homodimer. Interacts with AGO4, RPB205 and DRM2. Part of the chromatin-remodeling complex (DDR complex) that contains at least DRD1, DMS3 and RDM1. The DDR complex recruits/activates the RNA polymerases V and acts during siRNA-directed DNA methylation (RdDM). Peri-nucleolar. Impaired accumulation of siRNAs, reduced DNA methylation, and loss of transcriptional gene silencing at RdDM target loci. Impaired RNA polymerase V-chromatin associations (Pol V).