For a first post, I thought I’d talk about a method that many working on post-translationally-modified biomolecules may have used (or may want to be familiar with if they haven’t!)
Most of us are familiar with the Western Blot, named by the Towbin lab in reference to the Southern blot. The Southern was named after its originator, and the Northern and Western followed suit to fill out the cardinal directions. But many a molecular biologist has wondered, what about the Eastern blot? For that matter, what about all those other directions on the compass (North-East, North-West, etc.)?
So is there an Eastern blot? The answer may range from telling you its a myth, or its a trick question you’ll find on an exam. Well, dear reader, I’m here to tell you that’s just not so. First of all, it only takes one paper to christen a new method – and as it turns out the “Eastern blot” has more than a few folks claiming to have named it. However, its probably fair to say that if the name doesn’t catch on with other authors it doesn’t really matter much.
How many times has the Eastern blot been named? At least 10 different times by my count. And are they all the same? Not really.
As far as I’ve been able to find, the first use of the term “Eastern Blot” was in 1984, though it was called a “Middle-Eastern Blot“. An earlier paper had even talked about the term, but decided to not use it. Ishikawa & Taki introduced the term “Far-Eastern blotting” around 2000, but it wasn’t until 2001 that an “Eastern blot” was defined.
Far-Eastern blotting was used to identify glycolipids, and Eastern blotting was for detecting glycoconjugates (in this case protein-glycan conjugates.)
But why stop there? Eastern blotting has been used to describe:
- Western blots run with opposite polarity
- Immunoblots that use aptamers as the probe
- Detection of fusion proteins by complementation
- Detection of glycated proteins
- Detection of natural-product protein conjugates
Its perhaps reassuring that opinions may have started to merge on what an Eastern blot is. A few recent papers seem to refer to a blot for glycoconjugates with lectin probes as Eastern blots. These may include protein or lipid glyco-conjugates. Some examples:
- Mariappa et al., Sci. Signaling (2011)
- Maury et al., Stem Cell Res (2013)
- Nicolas & Nelson, J. Invest. Dermat. (2013)
Its worth pointing out that we could just as well refer to an Eastern blot where the probe is a lectin as “Lectin blotting.” This term likely predates any of the uses of Eastern blotting, and seems to show up in the literature more often (and with more consistent definitions.) A Google Scholar search for “lectin blotting” since 2012 gives over 200 hits.
So – word to the wise: If you still think “Eastern blotting” hasn’t been defined, you might want to repeat your lit search.
[Full disclosure: I’ve contributed many of these references, and some commentary which has since been deleted, to the wikipedia page on Eastern blotting a while back. So, if you notice some similarities to the article, that’s why.]