• Product name

  • Description

    Rabbit polyclonal to CBX4
  • Host species

  • Specificity

    In immunofluoresence, this antibody detects the expected discrete nuclear structure that is termed the PcG body, corresponding to the known localisation of PC2. The antibody has been successfully used to detect FLAG-tagged transfected hPC2 (see picture). It detects a weak band that probably corresponds to endogenous PC2, however, a strong secondary band is also seen at 50kD in all cell lines thus far tested. This suggests that the antibody also reacts with another ubiquitous highly expressed protein.
  • Tested applications

    Suitable for: ICC/IF, WBmore details
  • Species reactivity

    Reacts with: Human
  • Immunogen

    Synthetic peptide:


    , corresponding to amino acids 95 - 107 of Human PC2.

  • General notes

    PC2 and other members of the Drosophila Polycomb group gene family are part of a cellular memory system that is responsible for the inheritance of gene activity by progeny cells.



Our Abpromise guarantee covers the use of ab4189 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

Application Abreviews Notes
ICC/IF Use at an assay dependent dilution.
WB Use at an assay dependent dilution. Detects a band of approximately 82 kDa (predicted molecular weight: 61 kDa).


  • Function

    E3 SUMO-protein ligase which facilitates SUMO1 conjugation by UBE2I. Component of the Polycomb group (PcG) multiprotein PRC1 complex, a complex required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility.
  • Tissue specificity

  • Pathway

    Protein modification; protein sumoylation.
  • Sequence similarities

    Contains 1 chromo domain.
  • Post-translational

    Phosphorylated on Thr-497 by HIPK2 upon DNA damage; which enhances E3 SUMO-protein ligase activity and promotes sumoylation on Lys-494.
  • Cellular localization

  • Information by UniProt
  • Database links

  • Alternative names

    • CBX 4 antibody
    • CBX4 antibody
    • Cbx4 chromobox homolog 4 (Drosophila Pc class) antibody
    • CBX4_HUMAN antibody
    • Chromobox homolog 4 (Pc class homolog, Drosophila) antibody
    • Chromobox homolog 4 antibody
    • Chromobox protein homolog 4 antibody
    • E3 SUMO protein ligase CBX 4 antibody
    • E3 SUMO protein ligase CBX4 antibody
    • E3 SUMO-protein ligase CBX4 antibody
    • hPc 2 antibody
    • hPc2 antibody
    • NBP 16 antibody
    • NBP16 antibody
    • NS5ATP1 binding protein 16 antibody
    • Pc 2 antibody
    • Pc class 2 homolog antibody
    • Pc class homolog antibody
    • Pc class homolog Drosophila antibody
    • PC2 antibody
    • Polycomb 2 homolog antibody
    see all


  • Immunofluorescent imaging of human cells (U2OS) with ab4189 reveals the expected discrete nuclear structure that is termed the PcG body corresponding to the known localisation of PC2. This corresponds to results seen in Satijn et al.

    IF was performed with a standard paraformaldehyde technique (fixed in PBS buffered PFH 4% for 5 minutes, permeabilised with 0.5% triton-PBS for 5 minutes, blocked with 5% milk / 0.2% tween for one hour.  Primary antibody used at 1/200 in 5% milk / 0.2% TWEEN for one hour, secondary antibody for 30 minutes.  All blocking and incubation steps carried out at 37 degrees C. Nuclei counterstained with Hoechst stain (blue).

  • All lanes : Anti-CBX4 antibody (ab4189)

    Lane 1 : HEK 293 lysate over-expressing DDDDK tagged hPC2
    Lane 2 : HEK 293 lysate

    Predicted band size: 61 kDa
    Observed band size: 75 kDa
    why is the actual band size different from the predicted?
    Additional bands at: 30 kDa (possible non-specific secondary antibody binding), 49 kDa (possible non-specific secondary antibody binding), 65 kDa (possible non-specific secondary antibody binding)

    ab4189 specifically recognises over expressed DDDDK tagged hPC2 in HEK293 cells (lane1). The lower bands are assigned to degradation products.


This product has been referenced in:

  • MacPherson MJ  et al. The CTCF insulator protein is posttranslationally modified by SUMO. Mol Cell Biol 29:714-25 (2009). ICC/IF ; Human . Read more (PubMed: 19029252) »
See 1 Publication for this product

Customer reviews and Q&As


I'm sorry to hear you are having problems with ab4189, I would like to suggest a few modifications to your protocol: -try a different fixation step, I would suggest a 10min acetone or methanol (ice cold) fixation, it can be a very good fixative in ICC and can also help the permeabilisation to promote penetration of the antibody into the nucleus. -block the cells in 5%BSA in PBST (triton 0.3%) 30min-1hr -incubate the primary antibody overnight at a 1:200 dilution in PBST (triton 0.3%) -make sure the cytoplasmic staining you see is not caused by the secondary by omitting the primary antibody. The Alexa fluor antibodies are very powerful, you may wish to try more dilute antibody (1:1000, 1:2000) and incubate longer (1hr). I hope these suggestions will help, please let me know how you get on and do not hesitate to contact us again if you still have problems,

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