CBX8 Antibody [E24E8]

Catalog No.: F8896

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Biological Description

Specificity CBX8 Antibody [E24E8] detects endogenous levels of total CBX8 protein.
Background CBX8, or Chromobox protein homolog 8, is a member of the CBX family within the Polycomb Repressive Complex 1 (PRC1), partnering with proteins like RING1 and BMI1 to maintain heritable gene silencing during development and stem cell self-renewal. As a canonical H3K27me3 reader, CBX8 recruits PRC1 to specific chromatin regions, ensuring stable transcriptional repression. CBX8 contains an N-terminal chromodomain that forms an aromatic cage for H3K27me3 binding, an AT-hook motif that interacts with the DNA minor groove, and a C-terminal region responsible for PRC1 assembly and localization to Polycomb group (PcG) bodies in the nucleus. Its primary functions revolve around dynamic chromatin repression: CBX8 binds to H3K27me3-marked loci, compacts chromatin through multivalent PRC1 interactions, and ubiquitinates histone H2AK119 to inhibit RNA polymerase II progression. During embryonic stem cell differentiation, CBX8 facilitates the transition from PRC1-CBX7 to PRC1-CBX8, thereby supporting the robust activation of lineage-specific genes, such as the Hox clusters. CBX8 modulates repression of the INK4A-ARF locus to enable cells to bypass oncogene-induced senescence, promotes proliferation by derepressing cyclin genes, and colocalizes with BMI1 and RING1B in nuclear PcG bodies. Disease relevance includes its role in MLL-AF9 leukemia, where CBX8 is essential for HOX gene maintenance, its involvement in fibroblast immortalization, and its influence on hematopoietic stem cell self-renewal, with overexpression driving senescence bypass and knockdown leading to G1 arrest.

Usage Information

Application WB, IP, ChIP Dilution
WB IP CHIP
1:1000 1:200 1:50
Reactivity Human, Mouse, Rat, Monkey
Source Rabbit Monoclonal Antibody MW 65 kDa
Storage Buffer PBS, pH 7.2+50% Glycerol+0.05% BSA+0.01% NaN3
Storage
(from the date of receipt)
-20°C (avoid freeze-thaw cycles), 2 years
WB
Experimental Protocol:
 
Sample preparation
1. Tissue: Lyse the tissue sample by adding an appropriate volume of ice-cold RIPA/Nuclear Lysis Buffer (containing Protease Inhibitor Cocktail),and homogenize the tissue at a low temperature.
2. Adherent cell: Aspirate the culture medium and wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/Nuclear Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min.
3. Suspension cell: Transfer the culture medium to a pre-cooled centrifuge tube. Centrifuge and aspirate the supernatant. Wash the cells with ice-cold PBS twice. Lyse the cells by adding an appropriate volume of RIPA/Nuclear Lysis Buffer (containing Protease Inhibitor Cocktail) and put the sample on ice for 5 min.
4. Place the lysate into a pre-cooled microcentrifuge tube. Centrifuge at 4°C for 15 min. Collect the supernatant;
5. Remove a small volume of lysate to determine the protein concentration;
6. Combine the lysate with protein loading buffer. Boil 20 µL sample under 95-100°C for 5 min. Centrifuge for 5 min after cool down on ice.
 
Electrophoretic separation
1. According to the concentration of extracted protein, load appropriate amount of protein sample and marker onto SDS-PAGE gels for electrophoresis. Recommended separating gel (lower gel) concentration: 10%. Reference Table for Selecting SDS-PAGE Separation Gel Concentrations
2. Power up 80V for 30 minutes. Then the power supply is adjusted (110 V~150 V), the Marker is observed, and the electrophoresis can be stopped when the indicator band of the predyed protein Marker where the protein is located is properly separated. (Note that the current should not be too large when electrophoresis, too large current (more than 150 mA) will cause the temperature to rise, affecting the result of running glue. If high currents cannot be avoided, an ice bath can be used to cool the bath.)
 
Transfer membrane
1. Take out the converter, soak the clip and consumables in the pre-cooled converter;
2. Activate PVDF membrane with methanol for 1 min and rinse with transfer buffer;
3. Install it in the order of "black edge of clip - sponge - filter paper - filter paper - glue -PVDF membrane - filter paper - filter paper - sponge - white edge of clip";
4. The protein was electrotransferred to PVDF membrane. ( 0.45 µm PVDF membrane is recommended ) Reference Table for Selecting PVDF Membrane Pore Size Specifications
Recommended conditions for wet transfer: 200 mA, 120 min.
( Note that the transfer conditions can be adjusted according to the protein size. For high-molecular-weight proteins, a higher current and longer transfer time are recommended. However, ensure that the transfer tank remains at a low temperature to prevent gel melting.)
 
Block
1. After electrotransfer, wash the film with TBST at room temperature for 5 minutes;
2. Incubate the film in the blocking solution for 1 hour at room temperature;
3. Wash the film with TBST for 3 times, 5 minutes each time.
 
Antibody incubation
1. Use 5% skim milk powder to prepare the primary antibody working liquid (recommended dilution ratio for primary antibody 1:1000), gently shake and incubate with the film at 4°C overnight;
2. Wash the film with TBST 3 times, 5 minutes each time;
3. Add the secondary antibody to the blocking solution and incubate with the film gently at room temperature for 1 hour;
4. After incubation, wash the film with TBST 3 times for 5 minutes each time.
 
Antibody staining
1. Add the prepared ECL luminescent substrate (or select other color developing substrate according to the second antibody) and mix evenly;
2. Incubate with the film for 1 minute, remove excess substrate (keep the film moist), wrap with plastic film, and expose in the imaging system.

References

  • https://pubmed.ncbi.nlm.nih.gov/25500566/
  • https://pubmed.ncbi.nlm.nih.gov/17332741/

Application Data