Biolegend, 664913, Alexa Fluor® 647 anti-RNA Polymerase II RPB1 Antibody

RPB1 is the catalytic and largest component of RNA polymerase II, which synthesizes mRNA precursors and many functional non-coding RNAs. It forms the polymerase active center together with RPB2, the second largest subunit. Polymerase II (Pol II) is the central component of the basal RNA polymerase II transcription machinery. It is composed of mobile elements that move relatively to each other. RPB1 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 DNA template strand of the promoter is positioned within the central active site cleft of Pol II. Then, a bridging helix emanates from RPB1 and crosses the cleft near the catalytic site, which acts as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations during each neuocleotide addition. This promotes translocation of Pol II. Pol II moves on the template during transcription elongation. Elongation is influenced by the phosphorylation status of the C-terminal domain (CTD) of Pol II's largest subunit (RPB1), which serves as a platform for assembling factors that regulate transcription initiation, elongation, termination, and mRNA processing. It can act as a RNA-dependent RNA polymerase when associated with small delta antigen of Hepatitis delta virus, being able to conform as both a replicate and transcriptase for the viral RNA circular genome.