RNA Polymerase II, DNA-Directed, Polypeptide F (NRPB1) Antibody – Mouse Monoclonal

Function: DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Largest and catalytic component of RNA polymerase II which synthesizes mRNA precursors and many functional non-coding RNAs. Forms the polymerase active center together with the second largest subunit. Pol II is the central component of the basal RNA polymerase II transcription machinery. It is composed of mobile elements that move relative to each other. NRPB1 is part of the core element with the central large cleft, the clamp element that moves to open and close the cleft and the jaws that are thought to grab the incoming DNA template. At the start of transcription, a single-stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol II. A bridging helix emanates from NRPB1 and crosses the cleft near the catalytic site and is thought to promote translocation of Pol II by acting as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations at each step of nucleotide addition. During transcription elongation, Pol II moves on the template as the transcript elongates. Elongation is influenced by the phosphorylation status of the C-terminal domain (CTD) of Pol II largest subunit (NRPB1), which serves as a platform for assembly of factors that regulate transcription initiation, elongation, termination and mRNA processing

By similarity. Ref.7

Catalytic activity: Nucleoside triphosphate + RNA(n) = diphosphate + RNA(n+1).

Subunit structure: Component of the RNA polymerase II (Pol II) complex consisting of at least 12 subunits. Interacts with RDM1. Interacts (via CTD) with MED35A, MED35B and MED35C. Ref.6 Ref.7 Ref.8

Subcellular location: Nucleus. Note: Peri-nucleolar. Ref.8

Post-translational modification: The tandem 7 residues repeats in the C-terminal domain (CTD) can be highly phosphorylated. The phosphorylation activates Pol II. Phosphorylation occurs mainly at residues 'Ser-2' and 'Ser-5' of the heptapepdtide repeat. The phosphorylation state is believed to result from the balanced action of site-specific CTD kinases and phosphatase, and a 'CTD code' that specifies the position of Pol II within the transcription cycle has been proposed.

Miscellaneous: The binding of ribonucleoside triphosphate to the RNA polymerase II transcribing complex probably involves a two-step mechanism. The initial binding seems to occur at the entry (E) site and involves a magnesium ion temporarily coordinated by three conserved aspartate residues of the two largest RNA Pol II subunits. The ribonucleoside triphosphate is transferred by a rotation to the nucleotide addition (A) site for pairing with the template DNA. The catalytic A site involves three conserved aspartate residues of the RNA Pol II largest subunit which permanently coordinate a second magnesium ion.

Sequence similarities: Belongs to the RNA polymerase beta' chain family.

Sequence caution: The sequence CAA36735.1 differs from that shown. Reason: Erroneous gene model prediction.