RNA pol II CTD phospho Ser5 antibody (pAb)

Aliases: RPB1, RPO2, POLR2, POLRA, RPBh1, RPOL2, RpIILS, hsRPB1, hRPB220
Catalog No: 39749 Format: 100 µg $445 Buy
Catalog No: 39750 Format: 10 µg $105 Buy

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Antibody Type:
Protein A Chromatography
Molecular Weight:
210 kDa
Human, Mouse, Other (Wide Range)


ChIP Validated ChIP-Seq Validated Western Blot Validated

Application Notes

Validated Applications:
ChIP: 4 - 10 µg per ChIP
ChIP-Seq: 4 µl each
WB: 0.5 - 2 µg/ml dilution

Published Applications:


This RNA pol II CTD phospho Ser5 antibody was raised against synthetic peptide containing the RNA Pol II heptad repeat consensus sequence phosphorylated at serine 5.


Purified IgG in PBS (pH 7.5) with 30% glycerol and 0.035% sodium azide. Sodium azide is highly toxic. For your convenience, an unpurified serum version (Catalog No. 39233) of this antibody is also available.


RNA pol II CTD phospho Ser5 antibody (pAb) tested by ChIP-Seq.

RNA pol II CTD phospho Ser5 antibody (pAb) tested by ChIP-Seq.
ChIP was performed using the ChIP-IT® High Sensitivity Kit (Cat. No. 53040) with chromatin from 2.3 million HL-60 cells and 4 ul of antibody. ChIP DNA was sequenced on the Illumina HiSeq and 26 million sequence tags were mapped to identify RNA pol II phospho Ser5 binding. The image shows a 1.2 million base pair region on chromosome 15 with the expected enrichment at gene promoters.

RNA pol II CTD phospho Ser5 antibody (pAb) tested by ChIP.

RNA pol II CTD phospho Ser5 antibody tested by ChIP analysis.
Chromatin IP performed using the ChIP-IT® Express Kit (Catalog No. 53008) and HeLa Chromatin (1.5 x 106 cell equivalents per ChIP) using 10 µg of RNA pol II CTD phospho Ser5 antibody or the equivalent amount of rabbit IgG as a negative control. Real time, quantitative PCR (RT-qPCR) was performed on DNA purified from each of the ChIP reactions using a primer pair specific for the PABPC1 gene. Data are presented as Fold Enrichment of the ChIP antibody signal versus the negative control IgG (arbitrarily assigned a value of 1) using the ddCT method.

RNA pol II CTD phospho Ser5 antibody (pAb) tested by Western blot.

RNA pol II CTD phospho Ser5 antibody tested by Western blot.
Nuclear extract of HeLa cells (20 µg) probed with RNA pol II CTD phospho Ser5 antibody at a dilution of 0.5 µg/ml.

RNA pol II CTD phospho Ser5 antibody (pAb) tested by dot blot analysis.

RNA pol II CTD phospho Ser5 pAb tested by dot blot analysis.
Dot blot analysis was used to confirm the specificity of RNA pol II CTD phospho Ser5 antibody for phospho-Ser5 of the RNA Pol II C-terminal domain heptad repeat. Modified and unmodified peptides were spotted onto PVDF and probed with the antibody at a dilution of 0.2 µg/ml. Decreasing amounts of peptide were spotted in each row.
    Lane 1: Peptide phosphorylated at CTD repeat serine 2.
    Lane 2: Unmodified CTD repeat serine 2 peptide.
    Lane 3: Peptide phosphorylated at CTD repeat serine 5.
    Lane 4: Unmodified CTD repeat serine 5 peptide.


RNA pol II (RNA polymerase II) is responsible for synthesizing messenger RNA in eukaryotes. RNA pol II contains a carboxy terminal domain composed of heptapeptide repeats that are essential for polymerase activity. These repeats contain serine and threonine residues that are phosphorylated in actively transcribing RNA polymerase. In addition, RNA pol II, in combination with several other polymerase subunits, form the DNA binding domain of the polymerase, a groove in which the DNA template is transcribed into RNA.

During the transcription cycle, the CTD of the large subunit of RNA pol II is reversibly phosphorylated. RNA pol II containing unphosphorylated CTD is recruited to the promoter, whereas the hyperphosphorylated CTD form is involved in active transcription. Phosphorylation occurs at two sites within the heptapeptide repeat, at Serine 5 and Serine 2. RNA pol II Serine 5 phosphorylation is confined to promoter regions and is necessary for the initiation of transcription.

Positive Control

Active Motif's HeLa nuclear extract (Catalog No. 36010) can be used as a positive control for RNA pol II CTD phospho Ser5 antibody.

qPCR Primers

Active Motif's Human Positive Control Primer Set ACTB-2 (Cat. No. 71005) and Human Negative Control Primer Set 1 (Cat. No. 71001) have been validated for performing qPCR and endpoint PCR when this antibody has been used for ChIP on human samples. For ChIP experiments with this antibody on mouse samples, the Mouse Positive Control Primer Set Actb-2 (Cat. No. 71017) and Mouse Negative Control Primer Set 1 (Cat. No. 71011) have been validated for both qPCR and endpoint PCR.

Chromatin IP Assays

This antibody has been validated for use in ChIP and/or ChIP-Seq, and can be used with Active Motif's ChIP-IT® High Sensitivity Kit or our magnetic bead-based ChIP-IT® Express Kits. For an overview of all of our ChIP products, please visit our Chromatin IP Page to learn about ChIP products designed for use with RNA pol II CTD phospho Ser5 antibody (pAb).


Some products may be shipped at room temperature. This will not affect their stability or performance. Upon receipt, unconjugated antibodies may be stored at -20°C for up to 2 years. Fluorophore- & enzyme-conjugated antibodies should be stored at 4°C. Fluorophore-conjugated antibodies should be protected from light. Keep reagents on ice when not in storage; to avoid repeated freeze/thaw cycles, we recommend aliquoting items that will be stored frozen into single-use fractions prior to freezing.


This product is guaranteed for 6 months from date of receipt.

This product is for research use only and is not for use in diagnostic procedures.

Application Key

  • ChIP = Chromatin Immunoprecipitation;
  • DB = Dot Blot;
  • ELISA = Enzyme-linked Immunosorbent Assay;
  • EMSA = Electrophoretic Mobility Shift Assay
  • FC = Flow Cytometry;
  • ICC = Immunocytochemistry;
  • IF = Immunofluorescence;
  • IHC = Immunohistochemistry;
  • IP = Immunoprecipitation;
  • MeDIP = Methyl-DNA Immunoprecipitation;
  • TR-FRET = Time-Resolved Fluorescence Resonance Energy Transfer;
  • WB = Western Blotting