South Western Blotting - This method is widely used to find DNA binding proteins coding clones. In this method, the clones are lysed after replicaplating. Then the released proteins are absorbed onto the nitrocellulose membrane and incubated with the DNA molecule, which is labelled.

Normally the radiolabelled duplex DNA or oligonucleotide contains the sequence for which the DNA-binding protein is specific. Positive clones are selected by autoradiography method.

As this technique uses a radiolabelled DNA to detect polypeptide on the nitrocellulose membrane, this method is called as south western blotting. South western blotting is widely used to identify the transcript factors from the cDNA libraries.