Navigating the Sea of Blots

Contributed by Steve Anderson, Ph.D.

The terms Western blot, Southern blot, and Northern blot are so widely known, accepted, and used that we refer to them simply as Westerns, Southerns, and Northerns. Ever wonder how they got their names?

Navigating the sea of blots with Bethyl LabsIt all started in 1975 when a guy named Edwin Southern reported a method for detecting specific DNA sequences by separating them by electrophoresis, transferring them to a membrane, and probing the “blot” by hybridization with a radioactive DNA probe. This technique quickly became known as Southern blotting in homage to its inventor. After that, all subsequent probe and detection methods were named as a play on the original name “Southern”. Northern blotting was the next to be described, making its debut in 1977, followed by Western blotting in 1979. To date, those are the only names that have caught on and become widely accepted, although many other blotting techniques have been developed (see table below). For example, there is an Eastern blot, used for detecting post-translational modifications of proteins. The techniques used in Eastern blotting were actually available as early as 1976, but the name Eastern blotting never really caught on and remains controversial to this day. There is also a Southwestern blot, Far-Western blot, and Far-Eastern blot, and even some other, more obscure designations.

 

Year Blot Description
1975 Southern Detection of specific DNA sequences using a nucleic acid probe
1976 Eastern (not so named) Analysis of protein post-translational modifications, e.g. lipids, phospho, and carbohydrate moieties, using probes such as lectins
1977 Northern Detection of specific RNA or mRNA using a nucleic acid probe
1979 Western Detection of specific proteins, typically with antibodies
1980 Southwestern Detection of DNA-binding proteins using specific oligonucleotide probes
1994 Far-Eastern Analysis of lipids by HPTLC
2000 Far-Western Detection of protein-protein interactions using synthetic peptides or proteins as probes instead of antibodies

 

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References


Southern
Southern, EM. 1975. Detection of specific sequences among DNA fragments separated by gel electrophoresis. J Mol Biol. Nov 5;98(3):503–517.

Eastern
Tanner, MJ, Anstee, DJ. 1976. A method for the direct demonstration of the lectin-binding components of the human erythrocyte membrane. Biochem J. Feb 1;153(2):265–270.

Northern
Alwine JC, Kemp DJ, Stark GR. 1977. Method for detection of specific RNAs in agarose gels by transfer to diazobenzyloxymethyl-paper and hybridization with DNA probes. Proc. Natl. Acad. Sci. USA. Dec;74(12):5350–5354.

Western
Towbin H, Staehelin T, Gordon J. 1979. Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proc Natl Acad Sci USA. Sep;76(9):4350-4354.

Burnette WN. 1981. 'Western blotting': electrophoretic transfer of proteins from sodium dodecyl sulfate—polyacrylamide gels to unmodified nitrocellulose and radiographic detection with antibody and radioiodinated protein A. Anal Biochem. Apr;112(2):195–203.

Southwestern
Bowen B, Steinberg J, Laemmli UK, Weintraub H. 1980. The detection of DNA-binding proteins by protein blotting. Nucleic Acids Res. Jan 11;8(1):1–20.

Far-Eastern
Ishikawa D, Taki T. 1998. Micro-scale analysis of lipids by far-eastern blot (TLC blot). Nihon yukagaku kaishi. 47(10):963–970.

Far-Western
Burgress RR, Arthur TM, Pietz BC. 2000. Mapping protein-protein interaction domains using ordered fragment ladder far-western analysis of hexahistidine-tagged fusion proteins. Methods Enzymol. 328:141-157.