InterPro domain: IPR034012

The C-terminal zinc ribbon domain of subunit B9 in RNA polymerase (Pol) II (RPB9) is involved in intrinsic transcript cleavage [ 1 ]. Eukaryote genomes are transcribed by three nuclear RNA polymerases (Pol I, II and III) that share some subunits. RPB9 is homologous to RPA12 of Pol I and RPC11 of Pol III subunits but its intrinsic cleavage activity is weaker for Pol II [ 2 ]. RPB9 C-terminal zinc ribbon is homologous to Pol II elongation factor TFIIS domain III [ 3 ]. The very weak cleavage activity of Pol II is stimulated by TFIIS. RPB9 has two zinc-binding domains separated by a flexible linker [ 3 ].

1. RNA polymerase II subunit Rpb9 regulates transcription elongation in vivo. J. Biol. Chem. 275, 35506-11
2. Evolution of two modes of intrinsic RNA polymerase transcript cleavage. J. Biol. Chem. 286, 18701-7
3. Yeast RNA polymerase II subunit RPB9. Mapping of domains required for transcription elongation. J. Biol. Chem. 275, 2288-94