Nature Research, Nature Structural and Molecular Biology, 1(16), p. 91-93, 2008
DOI: 10.1038/nsmb.1539
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Genetic evidence indicates that plant-specific homologs of DNA-dependent RNA polymerase (Pol) II large subunits form Pol IV and Pol V complexes involved in small interfering RNA production and RNA-directed DNA methylation. Here we describe evidence that Pol V contains subunits shared with Pol II, but that RNA polymerase II subunit (RPB)-4 is missing from Pol V and that RPB5 is present as a Pol V–specific isomer, RPB5b. Pol V also has other proteins that are not present in Pol II, consistent with a role of this complex as an effector of silencing.