The northwestern blot combines the two techniques, and specifically involves the identification of labeled RNA that interact with proteins that are immobilized on a similar nitrocellulose membrane.
The technique involves using gel electrophoresis, an important analytical method that involves the use of an electric field and the subsequent migration of charged DNA, RNA or proteins through that electric field based on size and charge.
[8] This blocking solution assists with preventing non-specific binding of the primary and/or secondary antibodies to the nitrocellulose membrane.
Once washing is complete the blot is then typically developed by x-ray or similar autoradiography methods.
The location and concentration of the RNA binding protein on the blot can affect the results, and bands can sometimes appear after development.
Another advantage of the northwestern blot is that it aides in the building of expression libraries of cognate ligands.
[16] A noted disadvantage is that some RNA-Protein interactions with poor RNA binding properties may not be as detectable with this technique.