cd01435

Largest subunit (RPA1) of eukaryotic RNA polymerase I (RNAP I), N-terminal domain; RPA1 is the largest subunit of the eukaryotic RNA polymerase I (RNAP I). RNAP I is a multi-subunit protein complex responsible for the synthesis of rRNA precursors. RNAP I consists of at least 14 different subunits, the largest being homologous to subunit Rpb1 of yeast RNAP II and subunit beta' of bacterial RNAP. The yeast member of this family is known as Rpb190. 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. It makes up the head and core of one clamp, as well as the pore and funnel structures of RNAP II. The strong homology between RPA1 and Rpb1 suggests a similar functional and structural role.