ChIP-Exo-Seq-Validated Antibodies: know where your protein binds

The weakest link in every ChIP experiment

A chromatin immunoprecipitation (ChIP) experiment asks a deceptively simple question: where, across three billion base pairs of DNA, does your protein of interest actually bind? The answer depends entirely on one reagent: the primary antibody. An antibody that cross-reacts with off-target proteins pulls down the wrong DNA. An antibody whose epitope is masked by crosslinked chromatin pulls down nothing at all. Either way, weeks of sequencing and analysis are spent chasing noise.

This is why application-specific validation matters. An antibody that performs beautifully in Western blot has not thereby earned its place in a ChIP protocol. It has to be tested in chromatin, under crosslinking, in complex with DNA, against a non-specific IgG control.

From ChIP to ChIP-Exo-Seq: how resolution improves

ChIP, ChIP-Seq, and ChIP-Exo-Seq all start with the same step: immunoprecipitating a protein bound to DNA. They differ in how precisely they map the binding site and how much background they produce:

• ChIP with qPCR confirms that a protein binds within a broad region of more than 1000 bp.
• ChIP-Seq narrows the binding site to peaks of 100-300 bp across the genome.
• ChIP-Exo-Seq identifies the exact contact point at single base-pair resolution, with the lowest background.

Figure 1 shows these differences side by side. All Atlas Antibodies ChIP-validated antibodies are validated with ChIP-Exo-Seq, the highest of the three levels.

Chip-Exo-Seq: Validation at single base-pair resolution

Atlas Antibodies validates its ChIP-grade antibodies using ChIP-Exo-Seq, developed in collaboration with the laboratory of Prof. B. F. Pugh at Cornell University a pioneer of the ChIP-exo method.

ChIP-Exo-Seq adds an exonuclease digestion step to conventional ChIP-Seq: the enzyme trims unprotected DNA in the 5′→3′ direction and stops precisely at the protein-DNA crosslink. The result is sharp, strand-specific peaks marking exact binding sites at 1 bp resolution, with background DNA removed rather than merely averaged out.

Top 10 Chip-Exo-Seq-Validated Targets

The table below highlights ten widely studied chromatin-associated targets from the Atlas Antibodies ChIP-validated collection; each an affinity-purified Triple-A Polyclonal™.

The collection now spans more than 750 ChIP-validated antibodies against transcription factors, RNA polymerase II subunits, chromatin remodellers, and transcription-associated proteins, supported by peer-reviewed citations in the literature.

Every antibody carries an HPA identifier. Enter it at proteinatlas.org and the underlying characterization data (tissue profiles, cell line data, and application evidence) is openly published and freely browsable. Validation, in other words, is not a claim to take on trust; it is a record you can check before the antibody ever reaches your bench.

Ready to work with ChIP-Exo-Seq-validated antibodies?

Atlas Antibodies’ ChIP-Exo-Seq-validated antibodies are available through our webshop. Need help identifying the right antibody for your chromatin immunoprecipitation workflow? Our Account Managers and Technical Support team are happy to help you find the best fit for your research.