Back in the 2000’s most researchers spent their post-ChIP analysis looking at a gel or a PCR curve. Now, they spend their analysis time combing through hard drives of sequencing data. A lot has changed in the world of location analysis, but the need for good antibodies remains the same; which is probably why we hear a lot of different ChIP antibody adjectives being thrown around to separate the top performers from the pack. We asked Millipore what the deal is with the various flavors of ChIP antibodies out there to get a better idea of which ones are bitter or sweet.
ChIP Antibody Testing
A typical ChIP antibody gets tested by old the tried and true methods, like westerns and dot blots. That’s fine if that’s the application you’ll be using it for, but even if they pass those tests with flying colors, only a fraction of the abs will actually work in a ChIP setting. It turns out that there is no better way to test a ChIP antibody than to actually use it in a ChIP assay. That’s a lot of work, so only the most promising candidates move on to that stage. To address this, a number of vendors now sort their antibodies into various QC buckets.
ChIP Qualified Antibodies
ChIP qualified is a definite step up from the typical QC courses used out there. This label typically indicates that somebody in the company or in academia has used the antibody in a ChIP experiment. Sounds good to us. In many cases this might suffice, but antibodies can be fickle and lot-to-lot variability isn’t uncommon. So just because an antibody is labeled ChIP grade, doesn’t guarantee that it will work in ChIP. Something to think about next time your boss grills you about why the ChIP antibody used in that paper doesn’t also work well in your hands.
ChIP Validated Antibodies
ChIP validated is another step up the ladder from “ChIP qualified” or “ChIP grade” According to Michael Sturges, PhD, Sr. Product Manager for Epigenetics at EMD Millipore. In order to get the prestigious ChIPAb+ (their validated ChIP line) seal of approval, their abs need to complete an antibody pentathlon that’s more grueling than a season of Survivor. Here’s how it works:
- First they screen multiple candidate antibodies to find the best possible antibody.
- For this preliminary screening they apply a strict set of performance criteria: specificity, background, and the ability of the antibody to enrich for chromatin containing the target protein.
- Next, they employ a real-time PCR assay against a known positive location and known negative location to evaluate candidate antibody performance in ChIP.
- From there they select the best performing antibodies for development into a ChIPAb+
- Only these top performing antibodies are used to create a ChIPAb+ kit. This kit is more than just a validated antibody, it includes the control primers used in the QC, plus a negative control IgG antibody for customers to use in their own experiments.
- To avoid lot-to-lot variability that can occur with a standard ChIP grade antibody and guarantee successful ChIP, each and every lot of a ChIPAb+ antibody is validated in ChIP before it is put on the shelf.
ChIP Abs At The Top Of The Class
So, how many abs make the cut? According to Sturges, not very many. Although EMD Millipore offers a large number of antibodies qualified for ChIP, the valididated ChIPAb+ moniker is reserved only for the elite. “We currently offer over 55 different validated ChIPAB+ antibodies. The current collection targets key histone modifications and chromatin associated proteins. Our antibody validation program is ongoing, so there will be more ChIPAb+ kits coming out on a regular basis.”
Next time you’re in the market for ChIP Abs, check out the Millipore ChIPAb+ Kits to see if your favorite target made the list.