Largest subunit (Rpa1) of Eukaryotic RNA polymerase I (RNAP I), C-terminal domain
RNA polymerase I (RNAP I) is a multi-subunit protein complex responsible for the synthesis of rRNA precursor. It consists of at least 14 different subunits, and the largest one is homologous to subunit Rpb1 of yeast RNAP II and subunit beta' of bacterial RNAP. Rpa1 is also known as Rpa190 in yeast. Structure studies suggest that different RNAP complexes share a similar crab-claw-shape structure. The C-terminal domain of Rpb1, the largest subunit of RNAP II, makes up part of the foot and jaw structures of RNAP II. The similarity between this domain and the C-terminal domain of Rpb1, its counterpart in RNAP II, suggests a similar functional and structural role.