Northwestern blot

The northwestern blot, also known as the northwestern assay, is a hybrid analytical technique of the western blot and the northern blot, and is used in molecular biology to detect interactions between RNA and proteins. A related technique, the western blot, is used to detect a protein of interest that involves transferring proteins that are separated by gel electrophoresis onto a nitrocellulose membrane. A colored precipitate clusters along the band on the membrane containing a particular target protein. A northern blot is a similar analytical technique that, instead of detecting a protein of interest, is used to study gene expression by detection of RNA (or isolated mRNA) on a similar membrane. 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. Edwin Southern first created the Southern blot, an analytical technique used to detect DNA. 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. With a Southern Blot, the separated DNA fragments are then transferred to a filter membrane for detection. Detection occurs as bands become visible on the membrane and correlate with a particular molecule of interest. Subsequently, other similar blotting techniques were created with similar nomenclature to detect different molecules or interactions between molecules. These techniques include the western blot (protein detection), the northern blot (RNA detection), the southwestern blot (DNA-protein interaction detection), the eastern blot (post translational modification detection) and the northwestern blot (RNA-protein interaction detection). Running a northwestern blot involves separating the RNA binding proteins by gel electrophoresis, which will separate the RNA binding proteins based upon their size and charge.