Probable regulatory factor for several RNA polymerases. Effector involved in facilitation of Pol V transcription as RNA scaffold and recruitment of silencing complex to target genomic sites. Interacts with NRPD1. Associates with Pol II and Pol V complexes. Reduced DNA methylation at RdDM target loci and pleiotropic developmental phenotype. Belongs to the IWR1/SLC7A6OS family.