InterPro domain: IPR028363

Subunit RPB6/RPABC2 is a common component of eukaryotic RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and small RNAs, respectively. In RNA polymerase II (Pol II), RPB6/RPABC2 is part of the clamp element and together with parts of RPB1 and RPB2 forms a pocket to which the RPB4-RPB7 subcomplex binds [ 1 ].

In addition to RNA polymerases I, II, and III, the essential RNA polymerases present in all eukaryotes, plants have two additional nuclear RNA polymerases, abbreviated as Pol IV and Pol V, that play nonredundant roles in siRNA-directed DNA methylation and gene silencing. Pol IV and Pol V are composed of subunits that are paralogous or identical to the 12 subunits of Pol II, including subunit RPB6 [ 2 ].

1. Immunoaffinity purification and functional characterization of human transcription factor IIH and RNA polymerase II from clonal cell lines that conditionally express epitope-tagged subunits of the multiprotein complexes. J. Biol. Chem. 273, 34444-53
2. Subunit compositions of the RNA-silencing enzymes Pol IV and Pol V reveal their origins as specialized forms of RNA polymerase II. Mol. Cell 33, 192-203