background:
RNA polymerase II (Pol II) is an enzyme that is composed of twelve subunits and is responsible for the transcription of protein-coding genes. Transcription initiation requires Pol II-mediated recruitment of transcription machinery to a target promoter, thereby allowing transcription to begin. The largest subunit of Pol II (referred to as RPB1 or RPB205) is a 1,168 amino acid protein that contains one C2H2-type zinc finger and a SLCterminal domain comprised of several heptapeptide repeats. Although Pol II function requires the cooperation of all twelve subunits, the largest subunit conveys Pol II catalytic activity and, together with the second largest subunit, forms the active center of the Pol II enzyme. Additionally, the large subunit participates in forming the DNA-binding domain of Pol II, a groove that is necessary for transcription of the DNA template. Without proper function of the large subunit, mRNA synthesis and subsequent transcription elongation cannot occur.
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. 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 stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol II. A bridging helix emanates from RPB1 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 SLCterminal domain (CTD) of Pol II largest subunit (RPB1), which serves as a platform for assembly of factors that regulate transcription initiation, elongation, termination and mRNA processing. Acts as a RNA-dependent RNA polymerase when associated with small delta antigen of Hepatitis delta virus, acting both as a replicate and transcriptase for the viral RNA circular genome.
Subunit:
Component of the RNA polymerase II (Pol II) complex consisting of 12 subunits. The phosphorylated SLCterminal domain interacts with FNBP3 and SYNCRIP. Interacts with SAFB/SAFB1. Interacts with CCNL1 and MYO1C (By similarity). Interacts with CCNL2 and SFRS19. Component of a complex which is at least composed of HTATSF1/Tat-SF1, the P-TEFb complex components CDK9 and CCNT1, RNA polymerase II, SUPT5H, and NCL/nucleolin. Interacts with PAF1. Interacts (via SLCterminus) with FTSJD2, CTDSP1 and SCAF8. Interacts via the phosphorylated SLCterminal domain with WDR82 and with SETD1A and SETD1B only in the presence of WDR82. Interacts with ATF7IP. When phosphorylated at 'Ser-5', interacts with MEN1; the unphosphorylated form, or phosphorylated at 'Ser-2' does not interact. Interacts with DDX5.
Subcellular Location:
Nucleus.
Post-translational modifications:
Dephosphorylated by the protein phosphatase CTDSP1. [PTM] Ubiquitinated by WWP2 leading to proteasomal degradation (By similarity). [PTM] Methylated at Arg-1810 by CARM1. Methylation occurs only when the CTD is hypophosphorylated, and phosphorylation at Ser-365 and Ser-368 prevent methylation (in vitro). It is assumed that methylation occurs prior to phosphorylation and transcription initiation. CTD methylation may facilitate the expression of select RNAs.
Similarity:
Belongs to the RNA polymerase beta' chain family.
Database links:
UniProtKB/Swiss-Prot: P24928.2
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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