This family of proteins are eukaryotic RNA dependent RNA polymerases. These proteins are involved in post transcriptional gene silencing where they are thought to amplify dsRNA templates.

1: On the role of RNA amplification in dsRNA-triggered gene silencing. Sijen T, Fleenor J, Simmer F, Thijssen KL, Parrish S, Timmons L, Plasterk RH, Fire A; Cell 2001;107:465-476. PMID:11719187

2: An RNA-dependent RNA polymerase gene in Arabidopsis is required for posttranscriptional gene silencing mediated by a transgene but not by a virus. Dalmay T, Hamilton A, Rudd S, Angell S, Baulcombe DC; Cell 2000;101:543-553. PMID:10850496

3: Evolutionary connection between the catalytic subunits of DNA-dependent RNA polymerases and eukaryotic RNA-dependent RNA polymerases and the origin of RNA polymerases. Iyer LM, Koonin EV, Aravind L; BMC Struct Biol. 2003;3:1. PMID:12553882