Largest subunit (Rpb1) of Eukaryotic RNA polymerase II (RNAP II), C-terminal domain
RNA polymerase II (RNAP II) is a large multi-subunit complex responsible for the synthesis of mRNA. RNAP II consists of a 10-subunit core enzyme and a peripheral heterodimer of two subunits. The largest core subunit (Rpb1) of yeast RNAP II is the best characterized member of this family. Structure studies suggest that RNAP complexes from different organisms share a crab-claw-shape structure. In yeast, Rpb1 and Rpb2, the largest and the second largest subunits, each makes up one clamp, one jaw, and part of the cleft. Rpb1 interacts with Rpb2 to form the DNA entry and RNA exit channels in addition to the catalytic center of RNA synthesis. The C-terminal domain of Rpb1 makes up part of the foot and jaw structures.