What are the two subunits that make up the pincers of RNA polymerase (RNAP)?

The pincers of RNA polymerase (RNAP) are formed by two subunits known as B and B'. These subunits play a critical role in the enzyme's function, specifically in the transcription process. In eukaryotic RNA polymerase II, which is central to the transcription of protein-coding genes, the B and B' subunits are essential for the formation of the transcription bubble and the correct positioning of the RNA polymerase on the DNA template.

The B subunit is involved in binding to the template DNA and synthesizing the RNA strand, while the B' subunit provides a structural framework that allows for the coordination between the enzyme and the DNA. This pincer-like structure is vital for maintaining contact with the DNA during transcription and facilitating the movement of the enzyme along the DNA strand as it synthesizes RNA.

In contrast, the other options present different structures or components that do not represent the specific subunits responsible for the pincers of RNAP. For instance, Rpb1 and Rpb2 refer to the core subunits of RNA polymerase II but do not specifically denote the 'pincer' structure. Similarly, the β and α designations pertain to bacterial RNA polymerase components rather than the euk