cd02583

Largest subunit (RPC1) of eukaryotic RNA polymerase III (RNAP III), N-terminal domain; Rpc1 (C160) subunit forms part of the active site region of RNAP III. RNAP III is one of the three distinct classes of nuclear RNAP in eukaryotes that is responsible for the synthesis of tRNAs, 5SrRNA, Alu-RNA, U6 snRNA genes, and some others. RNAP III is the largest nuclear RNA polymerase with 17 subunits. Structure studies suggest that different RNA polymerase complexes share a similar crab-claw-shaped structure. The N-terminal domain of Rpb1, the largest subunit of RNAP II in yeast, forms part of the active site, making up the head and core of the one clamp, as well as the pore and funnel structures of RNAP II. The strong homology between Rpc1 and Rpb1 suggests a similar functional and structural role.