RNA polymerase-2 L' selections

RNA polymerase 2 largest subunit; RPB1; RNA polymerase 2 subunit A; RNA polymerase 2 subunit B1 (POLR2A)

Function: - largest & catalytic component of RNA polymerase 2 - forms the polymerase active center together with the 2nd largest subunit (POLR2B) - POLR2A is part of the core element with the central large cleft, the clamp element that moves to open & close the cleft & the jaws that are thought to grab the incoming DNA template - a bridging helix emanates from POLR2A & crosses the cleft near the catalytic site & is thought to promote translocation of RNA polymerase 2 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 - binding of ribonucleoside triphosphate to the RNA polymerase 2 transcribing complex probably involves a two- step mechanism - initial binding seems to occur at the entry (E) site & involves a Mg⁺² temporarily coordinated by 3 conserved Asp of the two largest RNA polymerase 2 subunits (POLR2A & POLR2B) - the ribonucleoside triphosphate is transferred by a rotation to the nucelotide addition (A) site for pairing with the template DNA - the catalytic A site involves 3 conserved Asp of POLR2A permanently coordinating a 2nd Mg⁺² - elongation is influenced by the phosphorylation status of the C-terminal domain (CTD) of POLR2A, which serves as a platform for assembly of factors that regulate transcription initiation, elongation, termination & mRNA processing - phosphorylated C-terminal domain interacts with FNBP3 & SYNCRIP - interacts with SAFB/SAFB1 - interacts with CCNL1 (putative) - interacts with CCNL2 & SFRS19 - component of a complex which is at least composed of HTATSF1/Tat-SF1, the P-TEFb complex components CDK9 & CCNT1, RNA polymerase 2, SUPT5H, & NCL/nucleolin - tandem 7 residues repeats in the C-terminal domain (CTD) can be highly phosphorylated a) phosphorylation activates RNA polymerase 2 b) occurs mainly at residues Ser-2 & Ser-5 of the heptapepdtide repeat c) phosphorylation state is believed to result from the balanced action of site-specific CTD kinases & phosphoprotein phosphatases, & a CTD code that specifies the position of RNA polymerase 2 within the transcription cycle Structure: - belongs to the RNA polymerase beta' chain family - contains 1 C2H2-type Zn⁺² finger Compartment: nucleus

General

C2H2 type zinc finger protein phosphoprotein RNA polymerase L'

Properties

SIZE: entity length = 1970 aa MW = 217 kD COMPARTMENT: cell nucleus MOTIF: Zn finger C2H2-type SITE: 71-87 EFFECTOR-BOUND: Zn+2 MOTIF: Zn+2-binding site SITE: 71-71 Zn+2-binding site SITE: 74-74 Zn+2-binding site SITE: 81-81 Zn+2-binding site SITE: 84-84 Zn+2-binding site SITE: 111-111 Zn+2-binding site SITE: 114-114 Tyr phosphorylation site {Y145} Zn+2-binding site SITE: 154-154 Zn+2-binding site SITE: 184-184 Mg+2-binding site SITE: 495-495 Mg+2-binding site SITE: 497-497 Mg+2-binding site SITE: 499-499 Bridging helix {833-845} repeat {1593-1960} MOTIF: consensus repeat {1593-1960} SEQUENCE-IS: Y-[ST]-P-[STQ]-[ST]-P-[SRTEVKGN] Ser phosphorylation site {S1878} Tyr phosphorylation site {Y1923} Ser phosphorylation site {S1927} Thr phosphorylation site {T1933} Ser phosphorylation site {S1934}

Database Correlations

OMIM 180660 UniProt P24928 PFAM correlations Kegg hsa:5430 ENZYME 2.7.7.6

References

Molecular Cell Biology (2nd ed) Darnell J; Lodish H & Baltimore D (eds), Scientific American Books, WH Freeman, NY 1990, pg 266
UniProt :accession P24928

Component-of

RNA polymerase-2