cd10508

C-terminal zinc ribbon domain of RPB9 subunit of RNA polymerase II; The C-terminal zinc ribbon domain (C_ribbon) of subunit B9 (C-ribbon_RPB9) in RNA polymerase (Pol) II is involved in intrinsic transcript cleavage. Eukaryote genomes are transcribed by three nuclear RNA polymerases (Pol I, II and III) that share some subunits. RPB9 have strong homology to RPA12 of Pol I and RPC11 of Pol III subunits but its intrinsic cleavage activity is weaker for Pol II. C-ribbon_RPB9 is homologous to Pol II elongation factor TFIIS domain III. The very weak cleavage activity of Pol II is stimulated by TFIIS. RPB9 has two zinc-binding domains separated by a flexible linker.