Binds to the promoter regions of RNA polymerase II and III small-nuclear RNA genes, type 3 RNA polymerase III non-coding RNA genes, small nucleolar RNAs and transfer RNA genes. Required for expression of mature 21U-RNAs. Diffuse nuclear localization. Concentrated in foci within nuclei of proliferating and pachytene germ cells. Foci localization is dependent on prde-1 activity. Broadly expressed in all tissues, including head, vulva and tail. Expressed throughout development. RNAi-mediated knockdown from larval stage L1 results in decreased 21U-RNA expression and disrupted distribution of prde-1 foci within the nuclei of germ cells.